1 files changed, 152 insertions, 0 deletions
diff --git a/doc/ebnf.py b/doc/ebnf.py
new file mode 100644
index 0000000..1989118
--- /dev/null
+++ b/doc/ebnf.py
@@ -0,0 +1,152 @@
+import string
+
+class EBNF:
+    IDENT   = 0
+    LITERAL = 2
+    LPAREN  = 3
+    LBRAK   = 4
+    LBRACE  = 5
+    BAR     = 6
+    EQL     = 7
+    RPAREN  = 8
+    RBRAK   = 9
+    RBRACE  = 10
+    PERIOD  = 11
+    OTHER   = 12
+
+    __input__  = None
+    __char__   = None
+    __symbol__ = None
+    __data__   = None
+
+    def __init__(self, input):
+        self.__input__ = input
+        self.__get_char__()
+
+    def __get_char__(self):
+        self.__char__ = self.__input__.read(1)
+        if self.__char__ == '':
+            raise EOFError
+        return self.__char__
+
+    def __get_sym__(self):
+        self.__data__ = None
+
+        while self.__char__ in string.whitespace:
+            self.__get_char__()
+
+        if self.__char__ in string.letters + "_":
+            self.__symbol__ = self.IDENT
+            self.__data__ = self.__char__
+            while self.__get_char__() in string.letters + "_":
+                self.__data__ += self.__char__
+            return
+
+        elif self.__char__ == '"':
+            self.__symbol__ = self.LITERAL
+            self.__data__ = ""
+            while self.__get_char__() != '"':
+                self.__data__ += self.__char__
+
+        elif self.__char__ == '=':
+            self.__symbol__ = self.EQL
+        elif self.__char__ == '(':
+            self.__symbol__ = self.LPAREN
+        elif self.__char__ == ')':
+            self.__symbol__ = self.RPAREN
+        elif self.__char__ == '[':
+            self.__symbol__ = self.LBRAK
+        elif self.__char__ == ']':
+            self.__symbol__ = self.RBRAK
+        elif self.__char__ == '{':
+            self.__symbol__ = self.LBRACE
+        elif self.__char__ == '}':
+            self.__symbol__ = self.RBRACE
+        elif self.__char__ == '|':
+            self.__symbol__ = self.BAR
+        elif self.__char__ == '.':
+            self.__symbol__ = self.PERIOD
+        else:
+            self.__symbol__ = self.OTHER
+
+        self.__get_char__()
+
+    def __error__(self, num):
+        pos = self.__input__.tell()
+        if pos > self.__lastpos__ + 2:
+            print "ERROR: pos=%d, err=%d, sym=%d" % (pos, num, self.__symbol__)
+            self.__lastpos__ = pos
+
+    def __expression__(self):
+        self.__term__()
+        while self.__symbol__ == self.BAR:
+            self.__get_sym__()
+            self.__term__()
+
+    def __term__(self):
+        self.__factor__()
+        while self.__symbol__ < self.BAR:
+            self.__factor__()
+
+    def __factor__(self):
+        if self.__symbol__ == self.IDENT:
+            print "record(TO, '%s', 1)" % (self.__data__,)
+            self.__get_sym__()
+        elif self.__symbol__ == self.LITERAL:
+            print "record(T1, '%s', 0)" % (self.__data__,)
+            self.__get_sym__()
+        elif self.__symbol__ == self.LPAREN:
+            self.__get_sym__()
+            self.__expression__()
+            if self.__symbol__ == self.RPAREN:
+                self.__get_sym__()
+            else:
+                self.__error__(2)
+        elif self.__symbol__ == self.LBRAK:
+            self.__get_sym__()
+            self.__expression__()
+            if self.__symbol__ == self.RBRAK:
+                self.__get_sym__()
+            else:
+                self.__error__(3)
+        elif self.__symbol__ == self.LBRACE:
+            self.__get_sym__()
+            self.__expression__()
+            if self.__symbol__ == self.RBRACE:
+                self.__get_sym__()
+            else:
+                self.__error__(4)
+        else:
+            self.__error__(5)
+
+    def __production__(self):
+        self.__get_sym__()
+
+        if self.__symbol__ == self.EQL:
+            self.__get_sym__()
+        else:
+            self.__error__(7)
+
+        self.__expression__()
+
+        if self.__symbol__ == self.PERIOD:
+            self.__get_sym__()
+        else:
+            self.__error__(8)
+
+    def __syntax__(self):
+        while self.__symbol__ == self.IDENT:
+            self.__production__()
+
+    def compile(self):
+        try:
+            self.__lastpos__ = 0
+            self.__get_sym__()
+            self.__syntax__()
+        except EOFError:
+            return
+
+if __name__ == '__main__':
+    import sys
+    ebnf = EBNF(sys.stdin)
+    ebnf.compile()