Method read_expr

web/template.py:249–372

Reads a python expression from the text and returns the expression and remaining text. expr -> simple_expr | paren_expr simple_expr -> id extended_expr extended_expr -> attr_access | paren_expr extended_expr | '' attr_access -> dot id extended_expr paren_expr

(self, text, escape=True)

        return StatementNode(line.strip() + "\n"), text

    def read_expr(self, text, escape=True):  # noqa: C901, PLR0915
        """Reads a python expression from the text and returns the expression and remaining text.

        expr -> simple_expr | paren_expr
        simple_expr -> id extended_expr
        extended_expr -> attr_access | paren_expr extended_expr | ''
        attr_access -> dot id extended_expr
        paren_expr -> [ tokens ] | ( tokens ) | { tokens }

            >>> read_expr = Parser().read_expr
            >>> read_expr("name")
            ($name, '')
            >>> read_expr("a.b and c")
            ($a.b, ' and c')
            >>> read_expr("a. b")
            ($a, '. b')
            >>> read_expr("name</h1>")
            ($name, '</h1>')
            >>> read_expr("(limit)ing")
            ($(limit), 'ing')
            >>> read_expr('a[1, 2][:3].f(1+2, "weird string[).", 3 + 4) done.')
            ($a[1, 2][:3].f(1+2, "weird string[).", 3 + 4), ' done.')
        """

        def simple_expr():
            identifier()
            extended_expr()

        def identifier():
            return next(tokens)

        def extended_expr():
            lookahead = tokens.peek()
            if lookahead is None:
                return
            elif lookahead.value == ".":
                attr_access()
            elif lookahead.value in parens:
                paren_expr()
                extended_expr()
            else:
                return

        def attr_access():
            from token import NAME  # python token constants

            if tokens[1].type == NAME:
                next(tokens)  # consume dot
                identifier()
                extended_expr()

        def paren_expr():
            begin = next(tokens).value
            end = parens[begin]
            while True:
                if tokens.peek().value in parens:
                    paren_expr()
                else: