Method parse_graminit_c

src/blib2to3/pgen2/conv.py:85–246

Parse the .c file written by pgen. (Internal) The file looks as follows. The first two lines are always this: #include "pgenheaders.h" #include "grammar.h" After that come four blocks: 1) one or more state definitions 2) a table defining dfas

(self, filename)

        return True

    def parse_graminit_c(self, filename):
        """Parse the .c file written by pgen.  (Internal)

        The file looks as follows.  The first two lines are always this:

        #include "pgenheaders.h"
        #include "grammar.h"

        After that come four blocks:

        1) one or more state definitions
        2) a table defining dfas
        3) a table defining labels
        4) a struct defining the grammar

        A state definition has the following form:
        - one or more arc arrays, each of the form:
          static arc arcs_<n>_<m>[<k>] = {
                  {<i>, <j>},
                  ...
          };
        - followed by a state array, of the form:
          static state states_<s>[<t>] = {
                  {<k>, arcs_<n>_<m>},
                  ...
          };

        """
        try:
            f = open(filename)
        except OSError as err:
            print(f"Can't open {filename}: {err}")
            return False
        # The code below essentially uses f's iterator-ness!
        lineno = 0

        # Expect the two #include lines
        lineno, line = lineno + 1, next(f)
        assert line == '#include "pgenheaders.h"\n', (lineno, line)
        lineno, line = lineno + 1, next(f)
        assert line == '#include "grammar.h"\n', (lineno, line)

        # Parse the state definitions
        lineno, line = lineno + 1, next(f)
        allarcs = {}
        states = []
        while line.startswith("static arc "):
            while line.startswith("static arc "):
                mo = re.match(r"static arc arcs_(\d+)_(\d+)\[(\d+)\] = {$", line)
                assert mo, (lineno, line)
                n, m, k = list(map(int, mo.groups()))
                arcs = []
                for _ in range(k):
                    lineno, line = lineno + 1, next(f)
                    mo = re.match(r"\s+{(\d+), (\d+)},$", line)
                    assert mo, (lineno, line)
                    i, j = list(map(int, mo.groups()))
                    arcs.append((i, j))