package refactor

thue/parser.py

@@ -0,0 +1,100 @@
+import re
+
+import lark
+from lark import Lark
+
+import thue.prods
+
+grammar = r'''
+program: suite
+
+suite: prod*
+
+?prod: _named_prod | _direct_prod
+
+_named_prod     : alias
+_direct_prod    : _compound_prod | _rule_prod | _literal_prod | _io_prod
+_io_prod  : output | input
+_compound_prod  : cont | sing
+_rule_prod      : full | part
+_literal_prod   : lit | ref
+
+alias : name "=" prod               // production alias
+output: "~" prod                    // output production
+input: ":::"                        // input production
+
+cont  : "{" suite "}"               // continual production
+sing  : "[" suite "]"               // singular production
+
+full  : _direct_prod "=>" prod      // full application
+part  : ctx "::=" prod              // partial application
+ref   : name                        // production reference
+
+lit   : STRING                      // literal production
+name  : CNAME                       // named production
+
+ctx   : REGEX
+
+CNAME : /[a-z_][a-z0-9_]*/i
+STRING: /(r)?(['"])(.*?)(?<!\\)\2/
+REGEX : /(r)?([\/])(.*?)(?<!\\)\2(i)?/
+
+%import common.WS
+%ignore WS
+'''
+
+STRING_PAT = re.compile(r'''(r)?(['"])(.*?)(?<!\\)\2''')
+REGEX_PAT = re.compile(r'''(r)?([/])(.*?)(?<!\\)\2(i)?''')
+ALL_PAT = re.compile(r'''^.*$''')
+
+
+class ProductionTransformer(lark.Transformer):
+    def suite(self, prods):
+        return thue.prods.Suite(prods)
+
+    def lit(self, prods):
+        fmt, = prods
+        match = STRING_PAT.match(fmt)
+        return thue.prods.Literal(match[3])
+
+    def ctx(self, prods):
+        reg, = prods
+        match = REGEX_PAT.match(reg)
+        return re.compile(match[3])
+
+    def input(self, prods):
+        return thue.prods.Input()
+
+    def output(self, prods):
+        prod, = prods
+        return thue.prods.Output(prod)
+
+    def full(self, prods):
+        lhs, rhs = prods
+        return thue.prods.Full(lhs, rhs)
+
+    def part(self, prods):
+        pat, rhs = prods
+        return thue.prods.Partial(pat, rhs)
+
+    def cont(self, prods):
+        suite, = prods
+        return thue.prods.Continual(suite)
+
+    def sing(self, prods):
+        suite, = prods
+        return thue.prods.Singular(suite)
+
+    def program(self, prods):
+        suite, = prods
+        return thue.prods.Program(suite)
+
+
+THUE_TRANSFORMER = ProductionTransformer()
+THUE_LARK = Lark(grammar, start='program')
+
+
+def compile(src):
+    tree = THUE_LARK.parse(src)
+    pgm = THUE_TRANSFORMER.transform(tree)
+    return pgm