Docs(TODO): Try Pyleri

[phdru.name/cgi-bin/blog-ru/search-tags.git] / parser / parser.py

diff --git a/parser/parser.py b/parser/parser.py
old mode 100644 (file)
new mode 100755 (executable)
index 68800ac..dbd0549
--- a/parser/parser.py
+++ b/parser/parser.py
@@ -1,110 +1,66 @@
-# Parse query
-
-from ply import lex, yacc
-
-literals = '()'
-
-tokens = ('NAME', 'AND_OP', 'OR_OP', 'NOT_OP', 'SP1')
-
-t_NAME = '[a-z][a-z0-9_]*'
-
-t_AND_OP = '&'
-
-t_OR_OP = r'\|'
-
-t_NOT_OP = '!'
-
-t_SP1 = '[ \t]+'
-
-def t_error(t):
-    """Avoid warnings on stderr"""
-
-lexer = lex.lex()
-
-def p_expression_name(p):
-    """expression : NAME"""
-    p[0] = ('NAME', p[1])
-
-def p_expression_and_and(p):
-    """expression : expression SP0 AND_OP AND_OP SP0 expression"""
-    p[0] = ('AND', p[1], p[6])
-
-def p_expression_and(p):
-    """expression : expression SP0 AND_OP SP0 expression"""
-    p[0] = ('AND', p[1], p[5])
-
-def p_expression_op_word(p):
-    """expression : l_expression op_word r_expression"""
-    if p[2] in ('AND', 'and'):
-        p[0] = ('AND', p[1], p[3])
-    elif p[2] in ('OR', 'or'):
-        p[0] = ('OR', p[1], p[3])
-
-def p_expression_or_or(p):
-    """expression : expression SP0 OR_OP OR_OP SP0 expression"""
-    p[0] = ('OR', p[1], p[6])
-
-def p_expression_or(p):
-    """expression : expression SP0 OR_OP SP0 expression"""
-    p[0] = ('OR', p[1], p[5])
-
-def p_expression_not(p):
-    """expression : NOT_OP SP0 expression"""
-    p[0] = ('NOT', p[3])
-
-def p_expression_in_parens(p):
-    """expression : expression_parens"""
-    p[0] = p[1]
-
-def p_l_expression(p):
-    """l_expression : expression_parens
-                    | expression SP1
-    """
-    if len(p) == 2:
-        p[0] = p[1]
-    elif len(p) == 3:
-        p[0] = p[1]
-    else:
-        raise ValueError(p)
-
-def p_r_expression(p):
-    """r_expression : expression_parens
-                    | SP1 expression
-    """
-    if len(p) == 2:
-        p[0] = p[1]
-    elif len(p) == 3:
-        p[0] = p[2]
-    else:
-        raise ValueError(p)
-
-def p_expression_parens(p):
-    """expression_parens : '(' SP0 expression SP0 ')'"""
-    p[0] = ('PARENS', p[3])
-
-def p_op_word(p):
-    """op_word : NAME"""
-    if p[1] in ('AND', 'and', 'OR', 'or'):
-        p[0] = p[1]
-    else:
-        raise SyntaxError
-
-def p_SP0(p):
-    """SP0 : SP1
-           | empty
-    """
-
-def p_empty(p):
-    """empty :"""
-
-def p_error(p):
-    """Avoid warnings on stderr"""
-    yacc.restart()
-
-precedence = (
-    ('left', 'OR_OP'),
-    ('left', 'AND_OP'),
-    ('right', 'NOT_OP'),
-)
-
-parser = yacc.yacc()
+#! /usr/bin/env python
+
+import os
+from lark import Lark, Transformer
+
+
+class TagsTransformer(Transformer):
+    def and_expression(self, items):
+        left = items[0]
+        right = items[2]
+        if len(items) > 3:
+            right = self.and_expression(items[2:])
+        return ('AND', left, right)
+
+    def or_expression(self, items):
+        left = items[0]
+        right = items[2]
+        if len(items) > 3:
+            right = self.or_expression(items[2:])
+        return ('OR', left, right)
+
+    def not_expression(self, items):
+        return ('NOT', items[1])
+
+    def expression_parens(self, items):
+        return ('PARENS', items[0])
+
+    def name(self, name):
+        return ('NAME', name[0].value)
+
+
+# cache
+_grammar = None
+
+
+def load_grammar():
+    global _grammar
+    parser_dir = os.path.dirname(__file__)
+    with open(os.path.join(parser_dir, 'grammar.ebnf'), 'rt') as grammar_file:
+        grammar_text = grammar_file.read()
+    grammar_lines = [line for line in grammar_text.splitlines()
+                     if not line.startswith('#')]
+    grammar_text = '\n'.join(grammar_lines)
+    _grammar = Lark(grammar_text)
+
+
+def parse(input):
+    if _grammar is None:
+        load_grammar()
+    tree = _grammar.parse(input)
+    return TagsTransformer().transform(tree)
+
+
+if __name__ == '__main__':
+    print '----------'
+    print parse('test')
+    print parse('!test')
+    print parse('not test')
+    print parse('foo or bar')
+    print parse('foo && bar')
+    print parse('foo && bar && baz')
+    print parse('!foo && bar && baz')
+    print parse('(test)')
+    print parse('(foo || bar)')
+    print parse('(foo and !bar)')
+    print '----------'