fonttools/Lib/fontTools/feaLib/lexer.py

from __future__ import print_function, division, absolute_import
from __future__ import unicode_literals


class LexerError(Exception):
    def __init__(self, message, location):
        Exception.__init__(self, message)
        self.location = location


class Lexer:
    NUMBER = "NUMBER"
    STRING = "STRING"
    NAME = "NAME"
    FILENAME = "FILENAME"
    CID = "CID"
    SYMBOL = "SYMBOL"
    COMMENT = "COMMENT"
    NEWLINE = "NEWLINE"

    CHAR_WHITESPACE_ = " \t"
    CHAR_NEWLINE_ = "\r\n"
    CHAR_SYMBOL_ = ";:@-+'{}[]<>()"
    CHAR_DIGIT_ = "0123456789"
    CHAR_LETTER_ = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
    CHAR_NAME_START_ = CHAR_LETTER_ + "_.\\"
    CHAR_NAME_CONTINUATION_ = CHAR_LETTER_ + CHAR_DIGIT_ + "_."

    MODE_NORMAL_ = "NORMAL"
    MODE_FILENAME_ = "FILENAME"

    def __init__(self, text, filename):
        self.filename_ = filename
        self.line_ = 1
        self.pos_ = 0
        self.line_start_ = 0
        self.text_ = text
        self.text_length_ = len(text)
        self.mode_ = Lexer.MODE_NORMAL_

    def __iter__(self):
        return self

    def next(self):  # Python 2
        return self.__next__()

    def __next__(self):  # Python 3
        while True:
            token_type, token, location = self.next_()
            if token_type not in {Lexer.COMMENT, Lexer.NEWLINE}:
                return (token_type, token, location)

    def next_(self):
        self.scan_over_(Lexer.CHAR_WHITESPACE_)
        column = self.pos_ - self.line_start_ + 1
        location = (self.filename_, self.line_, column)
        start = self.pos_
        text = self.text_
        limit = len(text)
        if start >= limit:
            raise StopIteration()
        cur_char = text[start]
        next_char = text[start + 1] if start + 1 < limit else None

        if cur_char == "\n":
            self.pos_ += 1
            self.line_ += 1
            self.line_start_ = self.pos_
            return (Lexer.NEWLINE, None, location)
        if cur_char == "\r":
            self.pos_ += (2 if next_char == "\n" else 1)
            self.line_ += 1
            self.line_start_ = self.pos_
            return (Lexer.NEWLINE, None, location)
        if cur_char == "#":
            self.scan_until_(Lexer.CHAR_NEWLINE_)
            return (Lexer.COMMENT, text[start:self.pos_], location)

        if self.mode_ is Lexer.MODE_FILENAME_:
            if cur_char != "(":
                raise LexerError("Expected '(' before file name", location)
            self.scan_until_(")")
            cur_char = text[self.pos_] if self.pos_ < limit else None
            if cur_char != ")":
                raise LexerError("Expected ')' after file name", location)
            self.pos_ += 1
            self.mode_ = Lexer.MODE_NORMAL_
            return (Lexer.FILENAME, text[start + 1:self.pos_ - 1], location)

        if cur_char == "\\" and next_char in Lexer.CHAR_DIGIT_:
            self.pos_ += 1
            self.scan_over_(Lexer.CHAR_DIGIT_)
            return (Lexer.CID, int(text[start + 1:self.pos_], 10), location)
        if cur_char in Lexer.CHAR_NAME_START_:
            self.pos_ += 1
            self.scan_over_(Lexer.CHAR_NAME_CONTINUATION_)
            token = text[start:self.pos_]
            if token == "include":
                self.mode_ = Lexer.MODE_FILENAME_
            return (Lexer.NAME, token, location)
        if cur_char in Lexer.CHAR_DIGIT_:
            self.scan_over_(Lexer.CHAR_DIGIT_)
            return (Lexer.NUMBER, int(text[start:self.pos_], 10), location)
        if cur_char == "-" and next_char in Lexer.CHAR_DIGIT_:
            self.pos_ += 1
            self.scan_over_(Lexer.CHAR_DIGIT_)
            return (Lexer.NUMBER, int(text[start:self.pos_], 10), location)
        if cur_char in Lexer.CHAR_SYMBOL_:
            self.pos_ += 1
            return (Lexer.SYMBOL, cur_char, location)
        if cur_char == '"':
            self.pos_ += 1
            self.scan_until_('"\r\n')
            if self.pos_ < self.text_length_ and self.text_[self.pos_] == '"':
                self.pos_ += 1
                return (Lexer.STRING, text[start + 1:self.pos_ - 1], location)
            else:
                raise LexerError("Expected '\"' to terminate string", location)
        raise LexerError("Unexpected character: '%s'" % cur_char, location)

    def scan_over_(self, valid):
        p = self.pos_
        while p < self.text_length_ and self.text_[p] in valid:
            p += 1
        self.pos_ = p

    def scan_until_(self, stop_at):
        p = self.pos_
        while p < self.text_length_ and self.text_[p] not in stop_at:
            p += 1
        self.pos_ = p