ANTLR grammar converter initial

lark/tools/antlr.py

@@ -0,0 +1,122 @@
+from lark import Lark, Transformer, Discard, v_args
+
+grammar = r"""
+start: statement+
+
+?statement: rule
+         | terminal
+         | "parser"? "grammar" name ";" -> ignore
+         | "options" _CODE -> ignore
+
+rule: RULE ":" expansions ";"
+terminal: "fragment"? TOKEN ":" term_expansions ";"
+
+?expansions: alias ("|" alias)*
+
+?alias: expansion ["#" name]
+
+?term_expansions: term_alias ("|" term_alias)*
+?term_alias: term_expansion ["->" name ["(" name ")"]]
+term_expansion: expr*
+
+?expansion: expr*
+
+?expr: atom OP?
+
+?atom: "(" expansions ")"
+     | value
+     | _CODE -> ignore
+     | "~" atom -> not_
+
+?value: name
+      | STRING -> string
+      | REGEXP -> regexp
+
+name: RULE
+    | TOKEN
+
+OP: /[+*][?]?|[?](?![a-z])/
+RULE: /[a-z][_a-zA-Z0-9]*/
+TOKEN: /[A-Z][_a-zA-Z0-9]*/
+REGEXP: /\[.*?\]|\./
+
+_STRING_INNER: /.*?/
+_STRING_ESC_INNER: _STRING_INNER /(?<!\\)(\\\\)*?/
+STRING : "'" _STRING_ESC_INNER "'"
+
+%import common.INT -> NUMBER
+%import common.WS
+
+COMMENT: /\s*/ "//" /[^\n]/*
+COMMENT2: /\/\*.*?\*\//s
+_CODE: /{.*?}/s
+
+%ignore WS
+%ignore COMMENT
+%ignore COMMENT2
+
+"""
+
+parser = Lark(grammar, parser='lalr')
+
+class T(Transformer):
+    def ignore(self, args):
+        raise Discard()
+
+    def expansions(self, x):
+        return '\n    | '.join(x)
+
+    def term_expansions(self, x):
+        return '\n    | '.join(x)
+
+    def term_alias(self, x):
+        # TODO channel hidden -> ignore
+        return x[0]
+
+    def expansion(self, x):
+        return "(" + ' '.join(x) + ")"
+
+    def term_expansion(self, x):
+        return "(" + ' '.join(x) + ")"
+
+    @v_args(inline=True)
+    def expr(self, expr, op):
+        return expr + op.value
+
+    @v_args(inline=True)
+    def rule(self, name, exprs):
+        return name + ": " + exprs
+
+    @v_args(inline=True)
+    def terminal(self, name, exprs):
+        if not isinstance(exprs, str):
+            breakpoint()
+        return name + ": " + exprs
+
+    @v_args(inline=True)
+    def name(self, t):
+        return t.value
+
+    @v_args(inline=True)
+    def string(self, t):
+        return t.value.replace('\\', '\\\\').replace('"', '\\"').replace("'", '"')
+
+    @v_args(inline=True)
+    def regexp(self, t):
+        return f'/{t.value}/'
+
+    @v_args(inline=True)
+    def not_(self, t):
+        return f" /(?!){t}/ "
+
+    def start(self, stmts):
+        return '\n\n'.join(stmts)
+
+
+with open('SQLite.g4') as f:
+    res = parser.parse(f.read())
+    # print('###', res.pretty())
+    res = T().transform(res)
+
+with open('sqlite.lark', 'w') as f:
+    f.write(res)