Class Parser

web/db.py:1581–1675

Parser to parse string templates like "Hello $name". Loosely based on (public domain, Ka-Ping Yee)

class Parser:
    """Parser to parse string templates like "Hello $name".

    Loosely based on <http://lfw.org/python/Itpl.py> (public domain, Ka-Ping Yee)
    """

    namechars = "abcdefghijklmnopqrstuvwxyz" "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"

    def __init__(self):
        self.reset()

    def reset(self):
        self.pos = 0
        self.level = 0
        self.text = ""

    def parse(self, text):
        """Parses the given text and returns a parse tree."""
        self.reset()
        self.text = text
        return self.parse_all()

    def parse_all(self):
        while True:
            dollar = self.text.find("$", self.pos)
            if dollar < 0:
                break
            nextchar = self.text[dollar + 1]
            if nextchar in self.namechars:
                yield _Node("text", self.text[self.pos : dollar])
                self.pos = dollar + 1
                yield self.parse_expr()

            # for supporting ${x.id}, for backward compatibility
            elif nextchar == "{":
                saved_pos = self.pos
                self.pos = dollar + 2  # skip "${"
                expr = self.parse_expr()
                if self.text[self.pos] == "}":
                    self.pos += 1
                    yield _Node("text", self.text[self.pos : dollar])
                    yield expr
                else:
                    self.pos = saved_pos
                    break
            else:
                yield _Node("text", self.text[self.pos : dollar + 1])
                self.pos = dollar + 1
                # $$ is used to escape $
                if nextchar == "$":
                    self.pos += 1

        if self.pos < len(self.text):
            yield _Node("text", self.text[self.pos :])

    def match(self):
        match = tokenprog.match(self.text, self.pos)
        if match is None: