'''
Created on 23 Sep 2010

@author: charles
'''
__license__   = 'GPL v3'
__copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'

import numbers
import re
import string
import traceback
from collections import OrderedDict
from functools import partial
from math import modf
from sys import exc_info

from calibre import prints
from calibre.constants import DEBUG
from calibre.ebooks.metadata.book.base import field_metadata
from calibre.utils.config import tweaks
from calibre.utils.formatter_functions import (
    StoredObjectType, formatter_functions, function_object_type, get_database,
)
from calibre.utils.icu import strcmp
from calibre.utils.localization import _
from polyglot.builtins import error_message


class Node:
    NODE_RVALUE = 1
    NODE_IF = 2
    NODE_ASSIGN = 3
    NODE_FUNC = 4
    NODE_COMPARE_STRING = 5
    NODE_COMPARE_NUMERIC = 6
    NODE_CONSTANT = 7
    NODE_FIELD = 8
    NODE_RAW_FIELD = 9
    NODE_CALL_STORED_TEMPLATE = 10
    NODE_ARGUMENTS = 11
    NODE_FIRST_NON_EMPTY = 12
    NODE_FOR = 13
    NODE_GLOBALS = 14
    NODE_SET_GLOBALS = 15
    NODE_CONTAINS = 16
    NODE_BINARY_LOGOP = 17
    NODE_UNARY_LOGOP = 18
    NODE_BINARY_ARITHOP = 19
    NODE_UNARY_ARITHOP = 20
    NODE_PRINT = 21
    NODE_BREAK = 22
    NODE_CONTINUE = 23
    NODE_RETURN = 24
    NODE_CHARACTER = 25
    NODE_STRCAT = 26
    NODE_BINARY_STRINGOP = 27
    NODE_LOCAL_FUNCTION_DEFINE = 28
    NODE_LOCAL_FUNCTION_CALL = 29
    NODE_RANGE = 30
    NODE_SWITCH = 31
    NODE_SWITCH_IF = 32

    def __init__(self, line_number, name):
        self.my_line_number = line_number
        self.my_node_name = name

    @property
    def node_name(self):
        return self.my_node_name

    @property
    def line_number(self):
        return self.my_line_number


class IfNode(Node):
    def __init__(self, line_number, condition, then_part, else_part):
        Node.__init__(self, line_number, 'if ...')
        self.node_type = self.NODE_IF
        self.condition = condition
        self.then_part = then_part
        self.else_part = else_part


class ForNode(Node):
    def __init__(self, line_number, variable, list_field_expr, separator, block):
        Node.__init__(self, line_number, 'for ...:')
        self.node_type = self.NODE_FOR
        self.variable = variable
        self.list_field_expr = list_field_expr
        self.separator = separator
        self.block = block


class RangeNode(Node):
    def __init__(self, line_number, variable, start_expr, stop_expr, step_expr, limit_expr, block):
        Node.__init__(self, line_number, 'for ...:')
        self.node_type = self.NODE_RANGE
        self.variable = variable
        self.start_expr = start_expr
        self.stop_expr = stop_expr
        self.step_expr = step_expr
        self.limit_expr = limit_expr
        self.block = block


class BreakNode(Node):
    def __init__(self, line_number):
        Node.__init__(self, line_number, 'break')
        self.node_type = self.NODE_BREAK


class ContinueNode(Node):
    def __init__(self, line_number):
        Node.__init__(self, line_number, 'continue')
        self.node_type = self.NODE_CONTINUE


class ReturnNode(Node):
    def __init__(self, line_number, expr):
        Node.__init__(self, line_number, 'return')
        self.expr = expr
        self.node_type = self.NODE_RETURN


class AssignNode(Node):
    def __init__(self, line_number, left, right):
        Node.__init__(self, line_number, 'assign to ' + left)
        self.node_type = self.NODE_ASSIGN
        self.left = left
        self.right = right


class FunctionNode(Node):
    def __init__(self, line_number, function_name, expression_list):
        Node.__init__(self, line_number, function_name + '()')
        self.node_type = self.NODE_FUNC
        self.name = function_name
        self.expression_list = expression_list


class StoredTemplateCallNode(Node):
    def __init__(self, line_number, name, function, expression_list):
        Node.__init__(self, line_number, 'call template: ' + name + '()')
        self.node_type = self.NODE_CALL_STORED_TEMPLATE
        self.name = name
        self.function = function  # instance of the definition class
        self.expression_list = expression_list


class LocalFunctionDefineNode(Node):
    def __init__(self, line_number, function_name, argument_list, block):
        Node.__init__(self, line_number, 'define local function' + function_name + '()')
        self.node_type = self.NODE_LOCAL_FUNCTION_DEFINE
        self.name = function_name
        self.argument_list = argument_list
        self.block = block

    def attributes_to_tuple(self):
        return (self.line_number, self.argument_list, self.block)


class LocalFunctionCallNode(Node):
    def __init__(self, line_number, name, arguments):
        Node.__init__(self, line_number, 'call local function: ' + name + '()')
        self.node_type = self.NODE_LOCAL_FUNCTION_CALL
        self.name = name
        self.arguments = arguments


class ArgumentsNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'arguments()')
        self.node_type = self.NODE_ARGUMENTS
        self.expression_list = expression_list


class GlobalsNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'globals()')
        self.node_type = self.NODE_GLOBALS
        self.expression_list = expression_list


class SetGlobalsNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'set_globals()')
        self.node_type = self.NODE_SET_GLOBALS
        self.expression_list = expression_list


class StringCompareNode(Node):
    def __init__(self, line_number, operator, left, right):
        Node.__init__(self, line_number, 'comparision: ' + operator)
        self.node_type = self.NODE_COMPARE_STRING
        self.operator = operator
        self.left = left
        self.right = right


class StringBinaryNode(Node):
    def __init__(self, line_number, operator, left, right):
        Node.__init__(self, line_number, 'binary operator: ' + operator)
        self.node_type = self.NODE_BINARY_STRINGOP
        self.operator = operator
        self.left = left
        self.right = right


class NumericCompareNode(Node):
    def __init__(self, line_number, operator, left, right):
        Node.__init__(self, line_number, 'comparison: ' + operator)
        self.node_type = self.NODE_COMPARE_NUMERIC
        self.operator = operator
        self.left = left
        self.right = right


class LogopBinaryNode(Node):
    def __init__(self, line_number, operator, left, right):
        Node.__init__(self, line_number, 'binary operator: ' + operator)
        self.node_type = self.NODE_BINARY_LOGOP
        self.operator = operator
        self.left = left
        self.right = right


class LogopUnaryNode(Node):
    def __init__(self, line_number, operator, expr):
        Node.__init__(self, line_number, 'unary operator: ' + operator)
        self.node_type = self.NODE_UNARY_LOGOP
        self.operator = operator
        self.expr = expr


class NumericBinaryNode(Node):
    def __init__(self, line_number, operator, left, right):
        Node.__init__(self, line_number, 'binary operator: ' + operator)
        self.node_type = self.NODE_BINARY_ARITHOP
        self.operator = operator
        self.left = left
        self.right = right


class NumericUnaryNode(Node):
    def __init__(self, line_number, operator, expr):
        Node.__init__(self, line_number, 'unary operator: '+ operator)
        self.node_type = self.NODE_UNARY_ARITHOP
        self.operator = operator
        self.expr = expr


class ConstantNode(Node):
    def __init__(self, line_number, value):
        Node.__init__(self, line_number, 'constant: ' + value)
        self.node_type = self.NODE_CONSTANT
        self.value = value


class VariableNode(Node):
    def __init__(self, line_number, name):
        Node.__init__(self, line_number, 'variable: ' + name)
        self.node_type = self.NODE_RVALUE
        self.name = name


class FieldNode(Node):
    def __init__(self, line_number, expression):
        Node.__init__(self, line_number, 'field()')
        self.node_type = self.NODE_FIELD
        self.expression = expression


class RawFieldNode(Node):
    def __init__(self, line_number, expression, default=None):
        Node.__init__(self, line_number, 'raw_field()')
        self.node_type = self.NODE_RAW_FIELD
        self.expression = expression
        self.default = default


class FirstNonEmptyNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'first_non_empty()')
        self.node_type = self.NODE_FIRST_NON_EMPTY
        self.expression_list = expression_list


class SwitchNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'first_non_empty()')
        self.node_type = self.NODE_SWITCH
        self.expression_list = expression_list


class SwitchIfNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'switch_if()')
        self.node_type = self.NODE_SWITCH_IF
        self.expression_list = expression_list


class ContainsNode(Node):
    def __init__(self, line_number, arguments):
        Node.__init__(self, line_number, 'contains()')
        self.node_type = self.NODE_CONTAINS
        self.value_expression = arguments[0]
        self.test_expression = arguments[1]
        self.match_expression = arguments[2]
        self.not_match_expression = arguments[3]


class PrintNode(Node):
    def __init__(self, line_number, arguments):
        Node.__init__(self, line_number, 'print')
        self.node_type = self.NODE_PRINT
        self.arguments = arguments


class CharacterNode(Node):
    def __init__(self, line_number, expression):
        Node.__init__(self, line_number, 'character()')
        self.node_type = self.NODE_CHARACTER
        self.expression = expression


class StrcatNode(Node):
    def __init__(self, line_number, expression_list):
        Node.__init__(self, line_number, 'strcat()')
        self.node_type = self.NODE_STRCAT
        self.expression_list = expression_list


class _Parser:
    LEX_OP = 1
    LEX_ID = 2
    LEX_CONST = 3
    LEX_EOF = 4
    LEX_STRING_INFIX = 5
    LEX_NUMERIC_INFIX = 6
    LEX_KEYWORD = 7
    LEX_NEWLINE = 8

    def error(self, message):
        ln = None
        try:
            tval = "'" + self.prog[self.lex_pos-1][1] + "'"
        except Exception:
            tval = _('Unknown')
        if self.lex_pos > 0 and self.lex_pos < self.prog_len:
            location = tval
            ln = self.line_number
        else:
            location = _('the end of the program')
        if ln:
            raise ValueError(_('{0}: {1} near {2} on line {3}').format(
                                          'Formatter', message, location, ln))
        else:
            raise ValueError(_('{0}: {1} near {2}').format(
                                          'Formatter', message, location))

    def check_eol(self):
        while self.lex_pos < len(self.prog) and self.prog[self.lex_pos] == self.LEX_NEWLINE:
            self.line_number += 1
            self.consume()

    def token(self):
        self.check_eol()
        try:
            token = self.prog[self.lex_pos][1]
            self.lex_pos += 1
            return token
        except:
            return None

    def consume(self):
        self.lex_pos += 1

    def token_op_is(self, op):
        self.check_eol()
        try:
            token = self.prog[self.lex_pos]
            return token[1] == op and token[0] == self.LEX_OP
        except:
            return False

    def token_op_is_string_infix_compare(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][0] == self.LEX_STRING_INFIX
        except:
            return False

    def token_op_is_numeric_infix_compare(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][0] == self.LEX_NUMERIC_INFIX
        except:
            return False

    def token_is_newline(self):
        return self.lex_pos < len(self.prog) and self.prog[self.lex_pos] == self.LEX_NEWLINE

    def token_is_id(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][0] == self.LEX_ID
        except:
            return False

    def token_is(self, candidate):
        self.check_eol()
        try:
            token = self.prog[self.lex_pos]
            return token[1] == candidate and token[0] == self.LEX_KEYWORD
        except:
            return False

    def token_is_keyword(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][0] == self.LEX_KEYWORD
        except:
            return False

    def token_is_constant(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][0] == self.LEX_CONST
        except:
            return False

    def token_is_eof(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][0] == self.LEX_EOF
        except:
            return True

    def token_text(self):
        self.check_eol()
        try:
            return self.prog[self.lex_pos][1]
        except:
            return _("'End of program'")

    def program(self, parent, funcs, prog):
        self.line_number = 1
        self.lex_pos = 0
        self.parent = parent
        self.funcs = funcs
        self.func_names = frozenset(set(self.funcs.keys()))
        self.prog = prog[0]
        self.prog_len = len(self.prog)
        self.local_functions = set()
        if prog[1] != '':
            self.error(_("Failed to scan program. Invalid input '{0}'").format(prog[1]))
        tree = self.expression_list()
        if not self.token_is_eof():
            self.error(_("Expected end of program, found '{0}'").format(self.token_text()))
        return tree

    def expression_list(self):
        expr_list = []
        while True:
            while self.token_is_newline():
                self.line_number += 1
                self.consume()
            if self.token_is_eof():
                break
            expr_list.append(self.top_expr())
            if self.token_op_is(';'):
                self.consume()
            else:
                break
        return expr_list

    def if_expression(self):
        self.consume()
        line_number = self.line_number
        condition = self.top_expr()
        if not self.token_is('then'):
            self.error(_("{0} statement: expected '{1}', "
                         "found '{2}'").format('if', 'then', self.token_text()))
        self.consume()
        then_part = self.expression_list()
        if self.token_is('elif'):
            return IfNode(line_number, condition, then_part, [self.if_expression(),])
        if self.token_is('else'):
            self.consume()
            else_part = self.expression_list()
        else:
            else_part = None
        if not self.token_is('fi'):
            self.error(_("{0} statement: expected '{1}', "
                         "found '{2}'").format('if', 'fi', self.token_text()))
        self.consume()
        return IfNode(line_number, condition, then_part, else_part)

    def for_expression(self):
        line_number = self.line_number
        self.consume()
        if not self.token_is_id():
            self.error(_("'{0}' statement: expected an identifier").format('for'))
        variable = self.token()
        if not self.token_is('in'):
            self.error(_("{0} statement: expected '{1}', "
                         "found '{2}'").format('for', 'in', self.token_text()))
        self.consume()
        if self.token_text() == 'range':
            is_list = False
            self.consume()
            if not self.token_op_is('('):
                self.error(_("{0} statement: expected '(', "
                         "found '{1}'").format('for', self.token_text()))
            self.consume()
            start_expr = ConstantNode(line_number, '0')
            step_expr = ConstantNode(line_number, '1')
            limit_expr = None
            stop_expr = self.top_expr()
            if self.token_op_is(','):
                self.consume()
                start_expr = stop_expr
                stop_expr = self.top_expr()
                if self.token_op_is(','):
                    self.consume()
                    step_expr = self.top_expr()
                    if self.token_op_is(','):
                        self.consume()
                        limit_expr = self.top_expr()
            if not self.token_op_is(')'):
                self.error(_("{0} statement: expected ')', "
                         "found '{1}'").format('for', self.token_text()))
            self.consume()
        else:
            is_list = True
            list_expr = self.top_expr()
            if self.token_is('separator'):
                self.consume()
                separator = self.expr()
            else:
                separator = None
        if not self.token_op_is(':'):
            self.error(_("{0} statement: expected '{1}', "
                         "found '{2}'").format('for', ':', self.token_text()))
        self.consume()
        block = self.expression_list()
        if not self.token_is('rof'):
            self.error(_("{0} statement: expected '{1}', "
                         "found '{2}'").format('for', 'rof', self.token_text()))
        self.consume()
        if is_list:
            return ForNode(line_number, variable, list_expr, separator, block)
        return RangeNode(line_number, variable, start_expr, stop_expr, step_expr, limit_expr, block)

    def define_function_expression(self):
        self.consume()
        line_number = self.line_number
        if not self.token_is_id():
            self.error(_("'{0}' statement: expected a function name identifier").format('def'))
        function_name = self.token()
        if function_name in self.local_functions:
            self.error(_("Function name '{0}' is already defined").format(function_name))
        if not self.token_op_is('('):
            self.error(_("'{0}' statement: expected a '('").format('def'))
        self.consume()
        arguments = []
        while not self.token_op_is(')'):
            a = self.top_expr()
            if a.node_type not in (Node.NODE_ASSIGN, Node.NODE_RVALUE):
                self.error(_("Parameters to a function must be "
                             "variables or assignments"))
            if a.node_type == Node.NODE_RVALUE:
                a = AssignNode(line_number, a.name, ConstantNode(self.line_number, ''))
            arguments.append(a)
            if not self.token_op_is(','):
                break
            self.consume()
        t = self.token()
        if t != ')':
            self.error(_("'{0}' statement: expected a ')' at end of argument list").format('def'))
        if not self.token_op_is(':'):
            self.error(_("'{0}' statement: missing ':'").format('def'))
        self.consume()
        block = self.expression_list()
        if not self.token_is('fed'):
            self.error(_("'{0}' statement: missing the closing '{1}'").format('def', 'fed'))
        self.consume()
        self.local_functions.add(function_name)
        return LocalFunctionDefineNode(line_number, function_name, arguments, block)

    def local_call_expression(self, name, arguments):
        return LocalFunctionCallNode(self.line_number, name, arguments)

    def call_expression(self, name, arguments):
        compiled_func = self.funcs[name].cached_compiled_text
        if compiled_func is None:
            text = self.funcs[name].program_text
            if function_object_type(text) is StoredObjectType.StoredGPMTemplate:
                text = text[len('program:'):]
                compiled_func = _Parser().program(self.parent, self.funcs,
                                            self.parent.lex_scanner.scan(text))
            elif function_object_type(text) is StoredObjectType.StoredPythonTemplate:
                text = text[len('python:'):]
                compiled_func = self.parent.compile_python_template(text)
            else:
                self.error(_("A stored template must begin with '{0}' or {1}").format('program:', 'python:'))
            self.funcs[name].cached_compiled_text = compiled_func
        return StoredTemplateCallNode(self.line_number, name, self.funcs[name], arguments)

    def top_expr(self):
        return self.or_expr()

    def or_expr(self):
        left = self.and_expr()
        while self.token_op_is('||'):
            self.consume()
            right = self.and_expr()
            left = LogopBinaryNode(self.line_number, 'or', left, right)
        return left

    def and_expr(self):
        left = self.not_expr()
        while self.token_op_is('&&'):
            self.consume()
            right = self.not_expr()
            left = LogopBinaryNode(self.line_number, 'and', left, right)
        return left

    def not_expr(self):
        if self.token_op_is('!'):
            self.consume()
            return LogopUnaryNode(self.line_number, 'not', self.not_expr())
        return self.string_binary_expr()

    def string_binary_expr(self):
        left = self.compare_expr()
        while self.token_op_is('&'):
            operator = self.token()
            right = self.compare_expr()
            left = StringBinaryNode(self.line_number, operator, left, right)
        return left

    def compare_expr(self):
        left = self.add_subtract_expr()
        if (self.token_op_is_string_infix_compare() or
                self.token_is('in') or self.token_is('inlist')):
            operator = self.token()
            return StringCompareNode(self.line_number, operator, left, self.add_subtract_expr())
        if self.token_op_is_numeric_infix_compare():
            operator = self.token()
            return NumericCompareNode(self.line_number, operator, left, self.add_subtract_expr())
        return left

    def add_subtract_expr(self):
        left = self.times_divide_expr()
        while self.token_op_is('+') or self.token_op_is('-'):
            operator = self.token()
            right = self.times_divide_expr()
            left = NumericBinaryNode(self.line_number, operator, left, right)
        return left

    def times_divide_expr(self):
        left = self.unary_plus_minus_expr()
        while self.token_op_is('*') or self.token_op_is('/'):
            operator = self.token()
            right = self.unary_plus_minus_expr()
            left = NumericBinaryNode(self.line_number, operator, left, right)
        return left

    def unary_plus_minus_expr(self):
        if self.token_op_is('+'):
            self.consume()
            return NumericUnaryNode(self.line_number, '+', self.unary_plus_minus_expr())
        if self.token_op_is('-'):
            self.consume()
            return NumericUnaryNode(self.line_number, '-', self.unary_plus_minus_expr())
        return self.expr()

    keyword_nodes = {
            'if':       (lambda self:None, if_expression),
            'for':      (lambda self:None, for_expression),
            'break':    (lambda self: self.consume(), lambda self: BreakNode(self.line_number)),
            'continue': (lambda self: self.consume(), lambda self: ContinueNode(self.line_number)),
            'return':   (lambda self: self.consume(), lambda self: ReturnNode(self.line_number, self.top_expr())),
            'def':      (lambda self: None, define_function_expression),
    }

    # {inlined_function_name: tuple(constraint on number of length, node builder) }
    inlined_function_nodes = {
        'field':            (lambda args: len(args) == 1,
                             lambda ln, args: FieldNode(ln, args[0])),
        'raw_field':        (lambda args: len(args) == 1,
                             lambda ln, args: RawFieldNode(ln, *args)),
        'test':             (lambda args: len(args) == 3,
                             lambda ln, args: IfNode(ln, args[0], (args[1],), (args[2],))),
        'first_non_empty':  (lambda args: len(args) >= 1,
                             lambda ln, args: FirstNonEmptyNode(ln, args)),
        'switch':           (lambda args: len(args) >= 3 and (len(args) %2) == 0,
                             lambda ln, args: SwitchNode(ln, args)),
        'switch_if':        (lambda args: len(args) > 0 and (len(args) %2) == 1,
                             lambda ln, args: SwitchIfNode(ln, args)),
        'assign':           (lambda args: len(args) == 2 and len(args[0]) == 1 and args[0][0].node_type == Node.NODE_RVALUE,
                             lambda ln, args: AssignNode(ln, args[0][0].name, args[1])),
        'contains':         (lambda args: len(args) == 4,
                             lambda ln, args: ContainsNode(ln, args)),
        'character':        (lambda args: len(args) == 1,
                             lambda ln, args: CharacterNode(ln, args[0])),
        'print':            (lambda _: True,
                             lambda ln, args: PrintNode(ln, args)),
        'strcat':           (lambda _: True,
                             lambda ln, args: StrcatNode(ln, args))
    }

    def expr(self):
        if self.token_op_is('('):
            self.consume()
            rv = self.expression_list()
            if not self.token_op_is(')'):
                self.error(_("Expected '{0}', found '{1}'").format(')', self.token_text()))
            self.consume()
            return rv

        # Check if we have a keyword-type expression
        if self.token_is_keyword():
            t = self.token_text()
            kw_tuple = self.keyword_nodes.get(t, None)
            if kw_tuple:
                # These are keywords, so there can't be ambiguity between these,
                # ids, and functions.
                kw_tuple[0](self)
                return kw_tuple[1](self)

        # Not a keyword. Check if we have an id reference or a function call
        if self.token_is_id():
            # We have an identifier. Check if it is a shorthand field reference
            line_number = self.line_number
            id_ = self.token()
            if len(id_) > 1 and id_[0] == '$':
                if id_[1] == '$':
                    return RawFieldNode(line_number, ConstantNode(self.line_number, id_[2:]))
                return FieldNode(line_number, ConstantNode(self.line_number, id_[1:]))

            # Do we have a function call?
            if not self.token_op_is('('):
                # Nope. We must have an lvalue (identifier) or an assignment
                if self.token_op_is('='):
                    # classic assignment statement
                    self.consume()
                    return AssignNode(line_number, id_, self.top_expr())
                return VariableNode(line_number, id_)

            # We have a function.
            # Check if it is a known one. We do this here so error reporting is
            # better, as it can identify the tokens near the problem.
            id_ = id_.strip()
            if id_ not in self.func_names and id_ not in self.local_functions:
                self.error(_('Unknown function {0}').format(id_))

            # Eat the opening paren, parse the argument list, then eat the closing paren
            self.consume()
            arguments = list()
            while not self.token_op_is(')'):
                # parse an argument expression (recursive call)
                arguments.append(self.expression_list())
                if not self.token_op_is(','):
                    break
                self.consume()
            t = self.token()
            if t != ')':
                self.error(_("Expected a '{0}' for function call, "
                             "found '{1}'").format(')', t))

            # Check for an inlined function
            function_tuple = self.inlined_function_nodes.get(id_, None)
            if function_tuple and function_tuple[0](arguments):
                return function_tuple[1](line_number, arguments)
            # More complicated special cases
            if id_ == 'arguments' or id_ == 'globals' or id_ == 'set_globals':
                new_args = []
                for arg_list in arguments:
                    arg = arg_list[0]
                    if arg.node_type not in (Node.NODE_ASSIGN, Node.NODE_RVALUE):
                        self.error(_("Parameters to '{0}' must be "
                                     "variables or assignments").format(id_))
                    if arg.node_type == Node.NODE_RVALUE:
                        arg = AssignNode(line_number, arg.name, ConstantNode(self.line_number, ''))
                    new_args.append(arg)
                if id_ == 'arguments':
                    return ArgumentsNode(line_number, new_args)
                if id_ == 'set_globals':
                    return SetGlobalsNode(line_number, new_args)
                return GlobalsNode(line_number, new_args)
            # Check for calling a local function template
            if id_ in self.local_functions:
                return self.local_call_expression(id_, arguments)
            # Check for calling a stored template
            if id_ in self.func_names and self.funcs[id_].object_type is not StoredObjectType.PythonFunction:
                return self.call_expression(id_, arguments)
            # We must have a reference to a formatter function. Check if
            # the right number of arguments were supplied
            cls = self.funcs[id_]
            if cls.arg_count != -1 and len(arguments) != cls.arg_count:
                self.error(_('Incorrect number of arguments for function {0}').format(id_))
            return FunctionNode(line_number, id_, arguments)
        elif self.token_is_constant():
            # String or number
            return ConstantNode(self.line_number, self.token())
        else:
            # Who knows what?
            self.error(_("Expected an expression, found '{0}'").format(self.token_text()))


class ExecutionBase(Exception):
    def __init__(self, name):
        super().__init__(_('{0} outside of for loop').format(name) if name else '')
        self.value = ''

    def set_value(self, v):
        self.value = v

    def get_value(self):
        return self.value


class ContinueExecuted(ExecutionBase):
    def __init__(self):
        super().__init__('continue')


class BreakExecuted(ExecutionBase):
    def __init__(self):
        super().__init__('break')


class ReturnExecuted(ExecutionBase):
    def __init__(self):
        super().__init__('return')


class StopException(Exception):
    def __init__(self):
        super().__init__('Template evaluation stopped')


class PythonTemplateContext:

    def __init__(self):
        # Set attributes we already know must exist.
        object.__init__(self)
        self.db = None
        self.arguments = None
        self.globals = None
        self.formatter = None
        self.funcs = None
        self.attrs_set = {'db', 'arguments', 'globals', 'funcs'}

    def set_values(self, **kwargs):
        # Create/set attributes from the named parameters. Doing it this way we
        # aren't required to change the signature of this method if/when we add
        # attributes in the future. However, if a user depends upon the
        # existence of some attribute and the context creator doesn't supply it
        # then the user will get an AttributeError exception.
        for k,v in kwargs.items():
            self.attrs_set.add(k)
            setattr(self, k, v)

    @property
    def attributes(self):
        # return a list of attributes in the context object
        return sorted(list(self.attrs_set))

    def __str__(self):
        # return a string of the attribute with values separated by newlines
        attrs = sorted(list(self.attrs_set))
        ans = OrderedDict()
        for k in attrs:
            ans[k] = getattr(self, k, None)
        return '\n'.join(f'{k}:{v}' for k,v in ans.items())


class FormatterFuncsCaller:
    '''
    Provides a convenient solution to call functions loaded in the
    TemplateFormatter. The functions are called using their name as an attribute
    of this class, with an underscore at the end if the name conflicts with a
    Python keyword. If the name contain a illegal character for a attribute
    (like .:-), use getattr(). Example: context.funcs.list_re_group()
    '''

    def __init__(self, formatter):
        if not isinstance(formatter, TemplateFormatter):
            raise TypeError(f'{formatter} is not an instance of TemplateFormatter')
        self.__formatter__ = formatter

    def __getattribute__(self, name):
        if name.startswith('__') and name.endswith('__'):  # return internal special attribute
            try:
                return object.__getattribute__(self, name)
            except Exception:
                pass

        formatter = self.__formatter__
        func_name = ''
        if name.endswith('_') and name[:-1] in formatter.funcs:  # give the priority to the backup name
            func_name = name[:-1]
        elif name in formatter.funcs:
            func_name = name

        if func_name:

            def call(*args, **kargs):
                def n(d):
                    return '' if d is None else str(d)
                args = tuple(n(a) for a in args)

                try:
                    if kargs:
                        raise ValueError(_('Keyword arguments are not allowed'))

                    # special function
                    if func_name == 'arguments':
                        raise ValueError(_("Don't call {0}. Instead use {1}").format('arguments()', 'context.arguments'))
                    if func_name == 'globals':
                        raise ValueError(_("Don't call {0}. Instead use {1}").format('globals()', 'context.globals'))
                    if func_name == 'set_globals':
                        raise ValueError(_("Don't call {0}. Instead use {1}").format('set_globals()', "context.globals['name'] = val"))
                    if func_name == 'character':
                        if _Parser.inlined_function_nodes['character'][0](args):
                            rslt = _Interpreter.characters.get(args[0])
                            if rslt is None:
                                raise ValueError(_("Invalid character name '{0}'").format(args[0]))
                        else:
                            raise ValueError(_('Incorrect number of arguments'))
                    else:
                        # built-in/user template functions and Stored GPM/Python templates
                        func = formatter.funcs[func_name]
                        if func.object_type == StoredObjectType.PythonFunction:
                            rslt = func.evaluate(formatter, formatter.kwargs, formatter.book, formatter.locals, *args)
                        else:
                            rslt = formatter._eval_sfm_call(func_name, args, formatter.global_vars)

                except Exception as e:
                    # Change the error message to return the name used in the template
                    e = e.__class__(_('Error in function {0} :: {1}').format(
                            name,
                            re.sub(r'\w+\.evaluate\(\)\s*', '', str(e), 1)))  # remove UserFunction.evaluate() | Builtin*.evaluate()
                    e.is_internal = True
                    raise e
                return rslt

            return call

        e = AttributeError(_("No function named {!r} exists").format(name))
        e.is_internal = True
        raise e

    def __dir__(self):
        return list(set(object.__dir__(self) +
                        list(self.__formatter__.funcs.keys()) +
                        [f+'_' for f in self.__formatter__.funcs.keys()]))


class _Interpreter:
    def error(self, message, line_number):
        m = _('Interpreter: {0} - line number {1}').format(message, line_number)
        raise ValueError(m)

    def program(self, funcs, parent, prog, val, is_call=False, args=None,
                global_vars=None, break_reporter=None):
        self.parent = parent
        self.parent_kwargs = parent.kwargs
        self.parent_book = parent.book
        self.funcs = funcs
        self.locals = {'$':val}
        self.local_functions = dict()
        self.override_line_number = None
        self.global_vars = global_vars if isinstance(global_vars, dict) else {}
        if break_reporter:
            self.break_reporter = self.call_break_reporter
            self.real_break_reporter = break_reporter
        else:
            self.break_reporter = None

        try:
            if is_call:
                # prog is an instance of the function definition class
                ret =  self.do_node_stored_template_call(StoredTemplateCallNode(1, prog.name, prog, None), args=args)
            else:
                ret = self.expression_list(prog)
        except ReturnExecuted as e:
            ret = e.get_value()
        return ret

    def call_break_reporter(self, txt, val, line_number):
        self.real_break_reporter(txt, val, self.locals,
                                 self.override_line_number if self.override_line_number
                                     else line_number)

    def expression_list(self, prog):
        val = ''
        try:
            for p in prog:
                val = self.expr(p)
        except (BreakExecuted, ContinueExecuted) as e:
            e.set_value(val)
            raise e
        return val

    def do_node_if(self, prog):
        line_number = prog.line_number
        test_part = self.expr(prog.condition)
        if self.break_reporter:
            self.break_reporter("'if': condition value", test_part, line_number)
        if test_part:
            v = self.expression_list(prog.then_part)
            if self.break_reporter:
                self.break_reporter("'if': then-block value", v, line_number)
            return v
        elif prog.else_part:
            v = self.expression_list(prog.else_part)
            if self.break_reporter:
                self.break_reporter("'if': else-block value", v, line_number)
            return v
        return ''

    def do_node_for(self, prog):
        line_number = prog.line_number
        try:
            separator = ',' if prog.separator is None else self.expr(prog.separator)
            v = prog.variable
            f = self.expr(prog.list_field_expr)
            res = getattr(self.parent_book, f, f)
            if res is not None:
                if isinstance(res, str):
                    res = [r.strip() for r in res.split(separator) if r.strip()]
                ret = ''
                if self.break_reporter:
                    self.break_reporter("'for' list value", separator.join(res), line_number)
                try:
                    for x in res:
                        try:
                            self.locals[v] = x
                            ret = self.expression_list(prog.block)
                        except ContinueExecuted as e:
                            ret = e.get_value()
                except BreakExecuted as e:
                    ret = e.get_value()
                if (self.break_reporter):
                    self.break_reporter("'for' block value", ret, line_number)
            elif self.break_reporter:
                # Shouldn't get here
                self.break_reporter("'for' list value", '', line_number)
                ret = ''
            return ret
        except (StopException, ValueError, ReturnExecuted) as e:
            raise e
        except Exception as e:
            self.error(_("Unhandled exception '{0}'").format(e), line_number)

    def do_node_range(self, prog):
        line_number = prog.line_number
        try:
            try:
                start_val = int(self.float_deal_with_none(self.expr(prog.start_expr)))
            except ValueError:
                self.error(_("{0}: {1} must be an integer").format('for', 'start'), line_number)
            try:
                stop_val = int(self.float_deal_with_none(self.expr(prog.stop_expr)))
            except ValueError:
                self.error(_("{0}: {1} must be an integer").format('for', 'stop'), line_number)
            try:
                step_val = int(self.float_deal_with_none(self.expr(prog.step_expr)))
            except ValueError:
                self.error(_("{0}: {1} must be an integer").format('for', 'step'), line_number)
            try:
                limit_val = (1000 if prog.limit_expr is None else
                         int(self.float_deal_with_none(self.expr(prog.limit_expr))))
            except ValueError:
                self.error(_("{0}: {1} must be an integer").format('for', 'limit'), line_number)
            var = prog.variable
            if (self.break_reporter):
                self.break_reporter("'for': start value", str(start_val), line_number)
                self.break_reporter("'for': stop value", str(stop_val), line_number)
                self.break_reporter("'for': step value", str(step_val), line_number)
                self.break_reporter("'for': limit value", str(limit_val), line_number)
            ret = ''
            try:
                range_gen = range(start_val, stop_val, step_val)
                if len(range_gen) > limit_val:
                    self.error(
                        _("{0}: the range length ({1}) is larger than the limit ({2})").format(
                            'for', str(len(range_gen)), str(limit_val)), line_number)
                for x in (str(x) for x in range_gen):
                    try:
                        if (self.break_reporter):
                            self.break_reporter(f"'for': assign to loop index '{var}'", x, line_number)
                        self.locals[var] = x
                        ret = self.expression_list(prog.block)
                    except ContinueExecuted as e:
                        ret = e.get_value()
            except BreakExecuted as e:
                ret = e.get_value()
            if (self.break_reporter):
                self.break_reporter("'for' block value", ret, line_number)
            return ret
        except (StopException, ValueError) as e:
            raise e
        except Exception as e:
            self.error(_("Unhandled exception '{0}'").format(e), line_number)

    def do_node_rvalue(self, prog):
        try:
            if (self.break_reporter):
                self.break_reporter(prog.node_name, self.locals[prog.name], prog.line_number)
            return self.locals[prog.name]
        except:
            self.error(_("Unknown identifier '{0}'").format(prog.name), prog.line_number)

    def do_node_func(self, prog):
        args = list()
        for arg in prog.expression_list:
            # evaluate the expression (recursive call)
            args.append(self.expr(arg))
        # Evaluate the function.
        id_ = prog.name.strip()
        cls = self.funcs[id_]
        res = cls.eval_(self.parent, self.parent_kwargs,
                        self.parent_book, self.locals, *args)
        if (self.break_reporter):
            self.break_reporter(prog.node_name, res, prog.line_number)
        return res

    def do_node_stored_template_call(self, prog, args=None):
        if (self.break_reporter):
            self.break_reporter(prog.node_name, _('before evaluating arguments'), prog.line_number)
        if args is None:
            args = []
            for arg in prog.expression_list:
                # evaluate the expression (recursive call)
                args.append(self.expr(arg))
        saved_locals = self.locals
        saved_local_functions = self.local_functions
        self.locals = {}
        self.local_functions = {}
        for dex, v in enumerate(args):
            self.locals['*arg_'+ str(dex)] = v
        if (self.break_reporter):
            self.break_reporter(prog.node_name, _('after evaluating arguments'), prog.line_number)
            saved_line_number = self.override_line_number
            self.override_line_number = (self.override_line_number if self.override_line_number
                                         else prog.line_number)
        else:
            saved_line_number = None
        try:
            if function_object_type(prog.function.program_text) is StoredObjectType.StoredGPMTemplate:
                val = self.expression_list(prog.function.cached_compiled_text)
            else:
                val = self.parent._run_python_template(prog.function.cached_compiled_text, args)
        except ReturnExecuted as e:
            val = e.get_value()
        self.override_line_number = saved_line_number
        self.locals = saved_locals
        self.local_functions = saved_local_functions
        if (self.break_reporter):
            self.break_reporter(prog.node_name + _(' returned value'), val, prog.line_number)
        return val

    def do_node_local_function_define(self, prog):
        if (self.break_reporter):
            self.break_reporter(prog.node_name, '', prog.line_number)
        self.local_functions[prog.name] = prog
        return ''

    def do_node_local_function_call(self, prog):
        if (self.break_reporter):
            self.break_reporter(prog.node_name, _('before evaluating arguments'), prog.line_number)
        line_number, argument_list, block  = self.local_functions[prog.name].attributes_to_tuple()
        if len(prog.arguments) > len(argument_list):
            self.error(_("Function {0}: argument count mismatch -- "
                         "{1} given, at most {2} required").format(prog.name,
                                                          len(prog.arguments),
                                                          len(argument_list)),
                       prog.line_number)
        new_locals = dict()
        for i,arg in enumerate(argument_list):
            if len(prog.arguments) > i:
                new_locals[arg.left] = self.expr(prog.arguments[i])
            else:
                new_locals[arg.left] = self.expr(arg.right)
        saved_locals = self.locals
        self.locals = new_locals
        if (self.break_reporter):
            self.break_reporter(prog.node_name, _('after evaluating arguments'), prog.line_number)
            saved_line_number = self.override_line_number
            self.override_line_number = (self.override_line_number if self.override_line_number
                                         else line_number)
        else:
            saved_line_number = None
        try:
            val = self.expr(block)
        except ReturnExecuted as e:
            val = e.get_value()
        finally:
            self.locals = saved_locals
            self.override_line_number = saved_line_number
        if (self.break_reporter):
            self.break_reporter(prog.node_name + _(' returned value'), val, prog.line_number)
        return val

    def do_node_arguments(self, prog):
        for dex, arg in enumerate(prog.expression_list):
            self.locals[arg.left] = self.locals.get('*arg_'+ str(dex), self.expr(arg.right))
        if (self.break_reporter):
            self.break_reporter(prog.node_name, '', prog.line_number)
        return ''

    def do_node_globals(self, prog):
        res = ''
        for arg in prog.expression_list:
            res = self.locals[arg.left] = self.global_vars.get(arg.left, self.expr(arg.right))
        if (self.break_reporter):
            self.break_reporter(prog.node_name, res, prog.line_number)
        return res

    def do_node_set_globals(self, prog):
        res = ''
        for arg in prog.expression_list:
            res = self.global_vars[arg.left] = self.locals.get(arg.left, self.expr(arg.right))
        if (self.break_reporter):
            self.break_reporter(prog.node_name, res, prog.line_number)
        return res

    def do_node_constant(self, prog):
        if (self.break_reporter):
            self.break_reporter(prog.node_name, prog.value, prog.line_number)
        return prog.value

    def do_node_field(self, prog):
        try:
            name = self.expr(prog.expression)
            try:
                res = self.parent.get_value(name, [], self.parent_kwargs)
                if (self.break_reporter):
                    self.break_reporter(prog.node_name, res, prog.line_number)
                return res
            except StopException:
                raise
            except:
                self.error(_("Unknown field '{0}'").format(name), prog.line_number)
        except (StopException, ValueError):
            raise
        except:
            self.error(_("Unknown field '{0}'").format('internal parse error'),
                       prog.line_number)

    def do_node_raw_field(self, prog):
        try:
            name = self.expr(prog.expression)
            name = field_metadata.search_term_to_field_key(name)
            res = getattr(self.parent_book, name, None)
            if res is None and prog.default is not None:
                res = self.expr(prog.default)
                if (self.break_reporter):
                    self.break_reporter(prog.node_name, res, prog.line_number)
                return res
            if res is not None:
                if isinstance(res, list):
                    fm = self.parent_book.metadata_for_field(name)
                    if fm is None:
                        res = ', '.join(res)
                    else:
                        res = fm['is_multiple']['list_to_ui'].join(res)
                else:
                    res = str(res)
            else:
                res = str(res)  # Should be the string "None"
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Unknown field '{0}'").format('internal parse error'),
                       prog.line_number)

    def do_node_assign(self, prog):
        t = self.expr(prog.right)
        self.locals[prog.left] = t
        if (self.break_reporter):
            self.break_reporter(prog.node_name, t, prog.line_number)
        return t

    def do_node_first_non_empty(self, prog):
        for expr in prog.expression_list:
            v = self.expr(expr)
            if v:
                if self.break_reporter:
                    self.break_reporter(prog.node_name, v, prog.line_number)
                return v
        if (self.break_reporter):
            self.break_reporter(prog.node_name, '', prog.line_number)
        return ''

    def do_node_switch(self, prog):
        val = self.expr(prog.expression_list[0])
        for i in range(1, len(prog.expression_list)-1, 2):
            v = self.expr(prog.expression_list[i])
            if re.search(v, val, flags=re.I):
                res = self.expr(prog.expression_list[i+1])
                if self.break_reporter:
                    self.break_reporter(prog.node_name, res, prog.line_number)
                return res
        res = self.expr(prog.expression_list[-1])
        if (self.break_reporter):
            self.break_reporter(prog.node_name, res, prog.line_number)
        return res

    def do_node_switch_if(self, prog):
        for i in range(0, len(prog.expression_list)-1, 2):
            tst = self.expr(prog.expression_list[i])
            if self.break_reporter:
                self.break_reporter("switch_if(): test expr", tst, prog.line_number)
            if tst:
                res = self.expr(prog.expression_list[i+1])
                if self.break_reporter:
                    self.break_reporter("switch_if(): value expr", res, prog.line_number)
                return res
        res = self.expr(prog.expression_list[-1])
        if (self.break_reporter):
            self.break_reporter("switch_if(): default expr", res, prog.line_number)
        return res

    def do_node_strcat(self, prog):
        res = ''.join([self.expr(expr) for expr in prog.expression_list])
        if self.break_reporter:
            self.break_reporter(prog.node_name, res, prog.line_number)
        return res

    def do_node_break(self, prog):
        if (self.break_reporter):
            self.break_reporter(prog.node_name, '', prog.line_number)
        raise BreakExecuted()

    def do_node_continue(self, prog):
        if (self.break_reporter):
            self.break_reporter(prog.node_name, '', prog.line_number)
        raise ContinueExecuted()

    def do_node_return(self, prog):
        v = self.expr(prog.expr)
        if (self.break_reporter):
            self.break_reporter(prog.node_name, v, prog.line_number)
        e = ReturnExecuted()
        e.set_value(v)
        raise e

    def do_node_contains(self, prog):
        v = self.expr(prog.value_expression)
        t = self.expr(prog.test_expression)
        if re.search(t, v, flags=re.I):
            res = self.expr(prog.match_expression)
        else:
            res = self.expr(prog.not_match_expression)
        if (self.break_reporter):
            self.break_reporter(prog.node_name, res, prog.line_number)
        return res

    INFIX_STRING_COMPARE_OPS = {
        "==": lambda x, y: strcmp(x, y) == 0,
        "!=": lambda x, y: strcmp(x, y) != 0,
        "<": lambda x, y: strcmp(x, y) < 0,
        "<=": lambda x, y: strcmp(x, y) <= 0,
        ">": lambda x, y: strcmp(x, y) > 0,
        ">=": lambda x, y: strcmp(x, y) >= 0,
        "in": lambda x, y: re.search(x, y, flags=re.I),
        "inlist": lambda x, y: list(filter(partial(re.search, x, flags=re.I),
                                           [v.strip() for v in y.split(',') if v.strip()]))
        }

    def do_node_string_infix(self, prog):
        try:
            left = self.expr(prog.left)
            right = self.expr(prog.right)
            res = '1' if self.INFIX_STRING_COMPARE_OPS[prog.operator](left, right) else ''
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Error during string comparison: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    INFIX_NUMERIC_COMPARE_OPS = {
        "==#": lambda x, y: x == y,
        "!=#": lambda x, y: x != y,
        "<#": lambda x, y: x < y,
        "<=#": lambda x, y: x <= y,
        ">#": lambda x, y: x > y,
        ">=#": lambda x, y: x >= y,
        }

    def float_deal_with_none(self, v):
        # Undefined values and the string 'None' are assumed to be zero.
        # The reason for string 'None': raw_field returns it for undefined values
        return float(v if v and v != 'None' else 0)

    def do_node_numeric_infix(self, prog):
        try:
            left = self.float_deal_with_none(self.expr(prog.left))
            right = self.float_deal_with_none(self.expr(prog.right))
            res = '1' if self.INFIX_NUMERIC_COMPARE_OPS[prog.operator](left, right) else ''
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Value used in comparison is not a number: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    LOGICAL_BINARY_OPS = {
        'and': lambda self, x, y: self.expr(x) and self.expr(y),
        'or': lambda self, x, y: self.expr(x) or self.expr(y),
    }

    def do_node_logop(self, prog):
        try:
            res = ('1' if self.LOGICAL_BINARY_OPS[prog.operator](self, prog.left, prog.right) else '')
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Error during operator evaluation: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    LOGICAL_UNARY_OPS = {
        'not': lambda x: not x,
    }

    def do_node_logop_unary(self, prog):
        try:
            expr = self.expr(prog.expr)
            res = ('1' if self.LOGICAL_UNARY_OPS[prog.operator](expr) else '')
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Error during operator evaluation: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    ARITHMETIC_BINARY_OPS = {
        '+': lambda x, y: x + y,
        '-': lambda x, y: x - y,
        '*': lambda x, y: x * y,
        '/': lambda x, y: x / y,
    }

    def do_node_binary_arithop(self, prog):
        try:
            answer = self.ARITHMETIC_BINARY_OPS[prog.operator](
                            self.float_deal_with_none(self.expr(prog.left)),
                            self.float_deal_with_none(self.expr(prog.right)))
            res = str(answer if modf(answer)[0] != 0 else int(answer))
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Error during operator evaluation: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    ARITHMETIC_UNARY_OPS = {
        '+': lambda x: x,
        '-': lambda x: -x,
    }

    def do_node_unary_arithop(self, prog):
        try:
            expr = self.ARITHMETIC_UNARY_OPS[prog.operator](float(self.expr(prog.expr)))
            res = str(expr if modf(expr)[0] != 0 else int(expr))
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Error during operator evaluation: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    def do_node_stringops(self, prog):
        try:
            res = self.expr(prog.left) + self.expr(prog.right)
            if (self.break_reporter):
                self.break_reporter(prog.node_name, res, prog.line_number)
            return res
        except (StopException, ValueError) as e:
            raise e
        except:
            self.error(_("Error during operator evaluation: "
                         "operator '{0}'").format(prog.operator), prog.line_number)

    characters = {
        'return':    '\r',
        'newline':   '\n',
        'tab':       '\t',
        'backslash': '\\',
    }

    def do_node_character(self, prog):
        try:
            key = self.expr(prog.expression)
            ret = self.characters.get(key, None)
            if ret is None:
                self.error(_("Function {0}: invalid character name '{1}")
                           .format('character', key), prog.line_number)
            if (self.break_reporter):
                self.break_reporter(prog.node_name, ret, prog.line_number)
        except (StopException, ValueError) as e:
            raise e
        return ret

    def do_node_print(self, prog):
        res = []
        for arg in prog.arguments:
            res.append(self.expr(arg))
        print(res)
        return res[0] if res else ''

    NODE_OPS = {
        Node.NODE_IF:                    do_node_if,
        Node.NODE_ASSIGN:                do_node_assign,
        Node.NODE_CONSTANT:              do_node_constant,
        Node.NODE_RVALUE:                do_node_rvalue,
        Node.NODE_FUNC:                  do_node_func,
        Node.NODE_FIELD:                 do_node_field,
        Node.NODE_RAW_FIELD:             do_node_raw_field,
        Node.NODE_COMPARE_STRING:        do_node_string_infix,
        Node.NODE_COMPARE_NUMERIC:       do_node_numeric_infix,
        Node.NODE_ARGUMENTS:             do_node_arguments,
        Node.NODE_CALL_STORED_TEMPLATE:  do_node_stored_template_call,
        Node.NODE_FIRST_NON_EMPTY:       do_node_first_non_empty,
        Node.NODE_SWITCH:                do_node_switch,
        Node.NODE_SWITCH_IF:             do_node_switch_if,
        Node.NODE_FOR:                   do_node_for,
        Node.NODE_RANGE:                 do_node_range,
        Node.NODE_GLOBALS:               do_node_globals,
        Node.NODE_SET_GLOBALS:           do_node_set_globals,
        Node.NODE_CONTAINS:              do_node_contains,
        Node.NODE_BINARY_LOGOP:          do_node_logop,
        Node.NODE_UNARY_LOGOP:           do_node_logop_unary,
        Node.NODE_BINARY_ARITHOP:        do_node_binary_arithop,
        Node.NODE_UNARY_ARITHOP:         do_node_unary_arithop,
        Node.NODE_PRINT:                 do_node_print,
        Node.NODE_BREAK:                 do_node_break,
        Node.NODE_CONTINUE:              do_node_continue,
        Node.NODE_RETURN:                do_node_return,
        Node.NODE_CHARACTER:             do_node_character,
        Node.NODE_STRCAT:                do_node_strcat,
        Node.NODE_BINARY_STRINGOP:       do_node_stringops,
        Node.NODE_LOCAL_FUNCTION_DEFINE: do_node_local_function_define,
        Node.NODE_LOCAL_FUNCTION_CALL:   do_node_local_function_call,
        }

    def expr(self, prog):
        try:
            if isinstance(prog, list):
                return self.expression_list(prog)
            return self.NODE_OPS[prog.node_type](self, prog)
        except (ValueError, ExecutionBase, StopException) as e:
            raise e
        except Exception as e:
            if (DEBUG):
                traceback.print_exc()
            self.error(_("Internal error evaluating an expression: '{0}'").format(str(e)),
                       prog.line_number)


class TemplateFormatter(string.Formatter):
    '''
    Provides a format function that substitutes '' for any missing value
    '''

    _validation_string = 'This Is Some Text THAT SHOULD be LONG Enough.%^&*'

    # Dict to do recursion detection. It is up to the individual get_value
    # method to use it. It is cleared when starting to format a template
    composite_values = {}

    def __init__(self):
        string.Formatter.__init__(self)
        self.book = None
        self.kwargs = None
        self.strip_results = True
        self.column_name = None
        self.template_cache = None
        self.global_vars = {}
        self.locals = {}
        self.funcs = formatter_functions().get_functions()
        self._interpreters = []
        self._template_parser = None
        self.recursion_stack = []
        self.recursion_level = -1
        self._caller = None
        self.python_context_object = None

    def _do_format(self, val, fmt):
        if not fmt or not val:
            return val
        if val == self._validation_string:
            val = '0'
        typ = fmt[-1]
        if typ == 's':
            pass
        elif 'bcdoxXn'.find(typ) >= 0:
            try:
                val = int(val)
            except Exception:
                raise ValueError(
                    _('format: type {0} requires an integer value, got {1}').format(typ, val))
        elif 'eEfFgGn%'.find(typ) >= 0:
            try:
                val = float(val)
            except:
                raise ValueError(
                    _('format: type {0} requires a decimal (float) value, got {1}').format(typ, val))
        return str(('{0:'+fmt+'}').format(val))

    def _explode_format_string(self, fmt):
        try:
            matches = self.format_string_re.match(fmt)
            if matches is None or matches.lastindex != 3:
                return fmt, '', ''
            return matches.groups()
        except:
            if DEBUG:
                traceback.print_exc()
            return fmt, '', ''

    format_string_re = re.compile(r'^(.*)\|([^\|]*)\|(.*)$', re.DOTALL)
    compress_spaces = re.compile(r'\s+')
    backslash_comma_to_comma = re.compile(r'\\,')

    arg_parser = re.Scanner([
                (r',', lambda x,t: ''),
                (r'.*?((?<!\\),)', lambda x,t: t[:-1]),
                (r'.*?\)', lambda x,t: t[:-1]),
        ])

    # ################# Template language lexical analyzer ######################

    lex_scanner = re.Scanner([
            (r'(==#|!=#|<=#|<#|>=#|>#)', lambda x,t: (_Parser.LEX_NUMERIC_INFIX, t)),  # noqa
            (r'(==|!=|<=|<|>=|>)',       lambda x,t: (_Parser.LEX_STRING_INFIX, t)),  # noqa
            (r'(if|then|else|elif|fi)\b',lambda x,t: (_Parser.LEX_KEYWORD, t)),  # noqa
            (r'(for|in|rof|separator)\b',lambda x,t: (_Parser.LEX_KEYWORD, t)),  # noqa
            (r'(separator|limit)\b',     lambda x,t: (_Parser.LEX_KEYWORD, t)),  # noqa
            (r'(def|fed|continue)\b',    lambda x,t: (_Parser.LEX_KEYWORD, t)),  # noqa
            (r'(return|inlist|break)\b', lambda x,t: (_Parser.LEX_KEYWORD, t)),  # noqa
            (r'(\|\||&&|!|{|})',         lambda x,t: (_Parser.LEX_OP, t)),  # noqa
            (r'[(),=;:\+\-*/&]',         lambda x,t: (_Parser.LEX_OP, t)),  # noqa
            (r'-?[\d\.]+',               lambda x,t: (_Parser.LEX_CONST, t)),  # noqa
            (r'\$\$?#?\w+',              lambda x,t: (_Parser.LEX_ID, t)),  # noqa
            (r'\$',                      lambda x,t: (_Parser.LEX_ID, t)),  # noqa
            (r'\w+',                     lambda x,t: (_Parser.LEX_ID, t)),  # noqa
            (r'".*?((?<!\\)")',          lambda x,t: (_Parser.LEX_CONST, t[1:-1])),  # noqa
            (r'\'.*?((?<!\\)\')',        lambda x,t: (_Parser.LEX_CONST, t[1:-1])),  # noqa
            (r'\n#.*?(?:(?=\n)|$)',      lambda x,t: _Parser.LEX_NEWLINE),  # noqa
            (r'\s',                      lambda x,t: _Parser.LEX_NEWLINE if t == '\n' else None),  # noqa
        ], flags=re.DOTALL)

    def _eval_program(self, val, prog, column_name, global_vars, break_reporter):
        if column_name is not None and self.template_cache is not None:
            tree = self.template_cache.get(column_name, None)
            if not tree:
                tree = self.gpm_parser.program(self, self.funcs, self.lex_scanner.scan(prog))
                self.template_cache[column_name] = tree
        else:
            tree = self.gpm_parser.program(self, self.funcs, self.lex_scanner.scan(prog))
        return self.gpm_interpreter.program(self.funcs, self, tree, val,
                                global_vars=global_vars, break_reporter=break_reporter)

    def _eval_sfm_call(self, template_name, args, global_vars):
        func = self.funcs[template_name]
        compiled_text = func.cached_compiled_text
        if func.object_type is StoredObjectType.StoredGPMTemplate:
            if compiled_text is None:
                compiled_text = self.gpm_parser.program(self, self.funcs,
                               self.lex_scanner.scan(func.program_text[len('program:'):]))
                func.cached_compiled_text = compiled_text
            return self.gpm_interpreter.program(self.funcs, self, func, None,
                                                is_call=True, args=args,
                                                global_vars=global_vars)
        elif function_object_type(func) is StoredObjectType.StoredPythonTemplate:
            if compiled_text is None:
                compiled_text = self.compile_python_template(func.program_text[len('python:'):])
                func.cached_compiled_text = compiled_text
            return self._run_python_template(compiled_text, args)

    def _eval_python_template(self, template, column_name):
        if column_name is not None and self.template_cache is not None:
            func = self.template_cache.get(column_name + '::python', None)
            if not func:
                func = self.compile_python_template(template)
                self.template_cache[column_name + '::python'] = func
        else:
            func = self.compile_python_template(template)
        return self._run_python_template(func, arguments=None)

    def _run_python_template(self, compiled_template, arguments):
        try:
            self.python_context_object.set_values(
                         db=get_database(self.book, get_database(self.book, None)),
                         globals=self.global_vars,
                         arguments=arguments,
                         formatter=self,
                         funcs=self._caller)
            rslt = compiled_template(self.book, self.python_context_object)
        except StopException:
            raise
        except Exception as e:
            stack = traceback.extract_tb(exc_info()[2])
            ss = stack[-1]
            if getattr(e, 'is_internal', False):
                # Exception raised by FormatterFuncsCaller
                # get the line inside the current template instead of the FormatterFuncsCaller
                for s in reversed(stack):
                    if s.filename == '<string>':
                        ss = s
                        break

            raise ValueError(_('Error in function {0} on line {1} : {2} - {3}').format(
                            ss.name, ss.lineno, type(e).__name__, str(e)))
        if not isinstance(rslt, str):
            raise ValueError(_('The Python template returned a non-string value: {!r}').format(rslt))
        return rslt

    def compile_python_template(self, template):
        def replace_func(mo):
            return mo.group().replace('\t', '    ')

        prog ='\n'.join([re.sub(r'^\t*', replace_func, line)
                                           for line in template.splitlines()])
        locals_ = {}
        if DEBUG and tweaks.get('enable_template_debug_printing', False):
            print(prog)
        try:
            exec(prog, locals_)
            func = locals_['evaluate']
            return func
        except SyntaxError as e:
            raise ValueError(
                _('Syntax error on line {0} column {1}: text {2}').format(e.lineno, e.offset, e.text))
        except KeyError:
            raise ValueError(_("The {0} function is not defined in the template").format('evaluate'))

    # ################# Override parent classes methods #####################

    def get_value(self, key, args, kwargs):
        raise Exception('get_value must be implemented in the subclass')

    def format_field(self, val, fmt):
        # ensure we are dealing with a string.
        if isinstance(val, numbers.Number):
            if val:
                val = str(val)
            else:
                val = ''
        # Handle conditional text
        fmt, prefix, suffix = self._explode_format_string(fmt)

        # Handle functions
        # First see if we have a functional-style expression
        if fmt.startswith('\''):
            p = 0
        else:
            p = fmt.find(':\'')
            if p >= 0:
                p += 1
        if p >= 0 and fmt[-1] == '\'':
            val = self._eval_program(val, fmt[p+1:-1], None, self.global_vars, None)
            colon = fmt[0:p].find(':')
            if colon < 0:
                dispfmt = ''
            else:
                dispfmt = fmt[0:colon]
        else:
            # check for old-style function references
            p = fmt.find('(')
            dispfmt = fmt
            if p >= 0 and fmt[-1] == ')':
                colon = fmt[0:p].find(':')
                if colon < 0:
                    dispfmt = ''
                    colon = 0
                else:
                    dispfmt = fmt[0:colon]
                    colon += 1

                fname = fmt[colon:p].strip()
                if fname in self.funcs:
                    func = self.funcs[fname]
                    if func.arg_count == 2:
                        # only one arg expected. Don't bother to scan. Avoids need
                        # for escaping characters
                        args = [fmt[p+1:-1]]
                    else:
                        args = self.arg_parser.scan(fmt[p+1:])[0]
                        args = [self.backslash_comma_to_comma.sub(',', a) for a in args]
                    if func.object_type is not StoredObjectType.PythonFunction:
                        args.insert(0, val)
                        val = self._eval_sfm_call(fname, args, self.global_vars)
                    else:
                        if (func.arg_count == 1 and (len(args) != 1 or args[0])) or \
                                (func.arg_count > 1 and func.arg_count != len(args)+1):
                            raise ValueError(
                                _('Incorrect number of arguments for function {0}').format(fname))
                        if func.arg_count == 1:
                            val = func.eval_(self, self.kwargs, self.book, self.locals, val)
                            if self.strip_results:
                                val = val.strip()
                        else:
                            val = func.eval_(self, self.kwargs, self.book, self.locals, val, *args)
                            if self.strip_results:
                                val = val.strip()
                else:
                    return _('%s: unknown function')%fname
        if val:
            val = self._do_format(val, dispfmt)
        if not val:
            return ''
        return prefix + val + suffix

    def evaluate(self, fmt, args, kwargs, global_vars, break_reporter=None):
        if fmt.startswith('program:'):
            ans = self._eval_program(kwargs.get('$', None), fmt[8:],
                                     self.column_name, global_vars, break_reporter)
        elif fmt.startswith('python:'):
            ans = self._eval_python_template(fmt[7:], self.column_name)
        else:
            ans = self.vformat(fmt, args, kwargs)
            if self.strip_results:
                ans = self.compress_spaces.sub(' ', ans)
        if self.strip_results:
            ans = ans.strip(' ')
        return ans

    # It is possible for a template to indirectly invoke other templates by
    # doing field references of composite columns. If this happens then the
    # reference can use different parameters when calling safe_format(). Because
    # the parameters are saved as instance variables they can possibly affect
    # the 'calling' template. To avoid this problem, save the current formatter
    # state when recursion is detected. Save state at level zero to be sure that
    # all class instance variables are restored to their base settings.

    def save_state(self):
        self.recursion_level += 1
        return (
            (self.strip_results,
             self.column_name,
             self.template_cache,
             self.kwargs,
             self.book,
             self.global_vars,
             self.funcs,
             self.locals,
             self._caller,
             self.python_context_object))

    def restore_state(self, state):
        self.recursion_level -= 1
        if state is None:
            raise ValueError(_('Formatter state restored before saved'))
        (self.strip_results,
         self.column_name,
         self.template_cache,
         self.kwargs,
         self.book,
         self.global_vars,
         self.funcs,
         self.locals,
         self._caller,
         self.python_context_object) = state

    # Allocate an interpreter if the formatter encounters a GPM or TPM template.
    # We need to allocate additional interpreters if there is composite recursion
    # so that the templates are evaluated by separate instances. It is OK to
    # reuse already-allocated interpreters because their state is initialized on
    # call. As a side effect, no interpreter is instantiated if no TPM/GPM
    # template is encountered.

    @property
    def gpm_interpreter(self):
        while len(self._interpreters) <= self.recursion_level:
            self._interpreters.append(_Interpreter())
        return self._interpreters[self.recursion_level]

    # Allocate a parser if needed. Parsers cannot recurse so one is sufficient.

    @property
    def gpm_parser(self):
        if self._template_parser is None:
            self._template_parser = _Parser()
        return self._template_parser

    # ######### a formatter that throws exceptions ############

    def unsafe_format(self, fmt, kwargs, book, strip_results=True, global_vars=None,
                      python_context_object=None):
        state = self.save_state()
        try:
            self._caller = FormatterFuncsCaller(self)
            self.strip_results = strip_results
            self.column_name = self.template_cache = None
            self.kwargs = kwargs
            self.book = book
            self.composite_values = {}
            self.locals = {}
            self.global_vars = global_vars if isinstance(global_vars, dict) else {}
            if isinstance(python_context_object, PythonTemplateContext):
                self.python_context_object = python_context_object
            else:
                self.python_context_object = PythonTemplateContext()
            return self.evaluate(fmt, [], kwargs, self.global_vars)
        finally:
            self.restore_state(state)

    # ######### a formatter guaranteed not to throw an exception ############

    def safe_format(self, fmt, kwargs, error_value, book,
                    column_name=None, template_cache=None,
                    strip_results=True, template_functions=None,
                    global_vars=None, break_reporter=None,
                    python_context_object=None):
        state = self.save_state()
        if self.recursion_level == 0:
            # Initialize the composite values dict if this is the base-level
            # call. Recursive calls will use the same dict.
            self.composite_values = {}
        try:
            self._caller = FormatterFuncsCaller(self)
            self.strip_results = strip_results
            self.column_name = column_name
            self.template_cache = template_cache
            self.kwargs = kwargs
            self.book = book
            self.global_vars = global_vars if isinstance(global_vars, dict) else {}
            if isinstance(python_context_object, PythonTemplateContext):
                self.python_context_object = python_context_object
            else:
                self.python_context_object = PythonTemplateContext()
            if template_functions:
                self.funcs = template_functions
            else:
                self.funcs = formatter_functions().get_functions()
            self.locals = {}
            try:
                ans = self.evaluate(fmt, [], kwargs, self.global_vars, break_reporter=break_reporter)
            except StopException as e:
                ans = error_message(e)
            except Exception as e:
                if DEBUG:
                    if tweaks.get('show_stack_traces_in_formatter', True):
                        traceback.print_exc()
                    if column_name:
                        prints('Error evaluating column named:', column_name)
                ans = error_value + ' ' + error_message(e)
            return ans
        finally:
            self.restore_state(state)


class ValidateFormatter(TemplateFormatter):
    '''
    Provides a formatter that substitutes the validation string for every value
    '''

    def get_value(self, key, args, kwargs):
        return self._validation_string

    def validate(self, x):
        from calibre.ebooks.metadata.book.base import Metadata
        return self.safe_format(x, {}, 'VALIDATE ERROR', Metadata(''))


validation_formatter = ValidateFormatter()


class EvalFormatter(TemplateFormatter):
    '''
    A template formatter that uses a simple dict instead of an mi instance
    '''

    def get_value(self, key, args, kwargs):
        if key == '':
            return ''
        key = key.lower()
        return kwargs.get(key, _('No such variable {0}').format(key))


# DEPRECATED. This is not thread safe. Do not use.
eval_formatter = EvalFormatter()
