Added test for template imports and implemented them

lark/load_grammar.py

@@ -525,8 +525,6 @@ class Grammar:
         # =================
         #  Compile Rules
         # =================
-        
-        # TODO: add templates
 
         # 1. Pre-process terminals
         transformer = PrepareLiterals() * PrepareSymbols() * PrepareAnonTerminals(terminals)  # Adds to terminals
@@ -640,7 +638,7 @@ def import_from_grammar_into_namespace(grammar, namespace, aliases):
 
     imported_terms = dict(grammar.term_defs)
     imported_rules = {n:(n,deepcopy(t),o) for n,t,o in grammar.rule_defs}
-    imported_temps = {n:(n,deepcopy(t),o) for n,t,o in grammar.temp_defs}
+    imported_temps = {n:(n,p,deepcopy(t),o) for n,p,t,o in grammar.temp_defs}
 
     term_defs = []
     rule_defs = []
@@ -649,12 +647,13 @@ def import_from_grammar_into_namespace(grammar, namespace, aliases):
     def rule_dependencies(symbol):
         if symbol.type != 'RULE':
             return []
-        try:
-            _, tree, _ = imported_rules[symbol]
-        except KeyError:
+        if symbol in imported_rules:
+            return _find_used_symbols(imported_rules[symbol][1])
+        elif symbol in imported_temps:
+            return _find_used_symbols(imported_temps[symbol][2]) - set(imported_temps[symbol][1])
+        else:
             raise GrammarError("Missing symbol '%s' in grammar %s" % (symbol, namespace))
 
-        return _find_used_symbols(tree)
 
 
     def get_namespace_name(name):
@@ -671,14 +670,24 @@ def import_from_grammar_into_namespace(grammar, namespace, aliases):
             term_defs.append([get_namespace_name(symbol), imported_terms[symbol]])
         else:
             assert symbol.type == 'RULE'
-            rule = imported_rules[symbol]
-            for t in rule[1].iter_subtrees():
-                for i, c in enumerate(t.children):
-                    if isinstance(c, Token) and c.type in ('RULE', 'TERMINAL'):
-                        t.children[i] = Token(c.type, get_namespace_name(c))
-            rule_defs.append((get_namespace_name(symbol), rule[1], rule[2]))
-
-    return term_defs, rule_defs
+            if symbol in imported_rules:
+                rule = imported_rules[symbol]
+                for t in rule[1].iter_subtrees():
+                    for i, c in enumerate(t.children):
+                        if isinstance(c, Token) and c.type in ('RULE', 'TERMINAL'):
+                            t.children[i] = Token(c.type, get_namespace_name(c))
+                rule_defs.append((get_namespace_name(symbol), rule[1], rule[2]))
+            else:
+                temp = imported_temps[symbol]
+                for t in temp[2].iter_subtrees():
+                    for i, c in enumerate(t.children):
+                        if isinstance(c, Token) and c.type in ('RULE', 'TERMINAL'):
+                            t.children[i] = Token(c.type, get_namespace_name(c))
+                params = [('%s__%s' if p[0]!='_' else '_%s__%s' ) % (namespace, p) for p in temp[1]]
+                temp_defs.append((get_namespace_name(symbol), params, temp[2], temp[3]))
+
+
+    return term_defs, rule_defs, temp_defs
 
 
 

tests/grammars/templates.lark

@@ -0,0 +1 @@
+sep{item, delim}: item (delim item)*

tests/test_parser.py

@@ -835,6 +835,13 @@ def _make_parser_test(LEXER, PARSER):
             x = g.parse("[1]")
             self.assertSequenceEqual(x.children,['1'])
 
+        def test_templates_import(self):
+            g = _Lark_open("test_templates_import.lark", rel_to=__file__)
+            x = g.parse("[1, 2, 3, 4]")
+            self.assertSequenceEqual(x.children,['1', '2', '3', '4'])
+            x = g.parse("[1]")
+            self.assertSequenceEqual(x.children,['1'])
+
         def test_token_collision_WS(self):
             g = _Lark(r"""start: "Hello" NAME
                         NAME: /\w/+

tests/test_templates_import.lark

@@ -0,0 +1,4 @@
+start: "[" sep{NUMBER, ","} "]"
+NUMBER: /\d+/
+%ignore " "
+%import .grammars.templates.sep