PR: Features/#515 improve rule declaration message (#519)

* Closes #515

CHANGELOG.md

@@ -3,6 +3,13 @@
 
 # SnakeCharm Plugin Changelog
 
+
+## [2024.1.2]
+Released on <not released>
+
+### Fixed
+- Improve parser error message when rule/module is declared with name but lacks ':' (see [#515](https://github.com/JetBrains-Research/snakecharm/issues/515))
+
 ## [2024.1.1]
 Released on 20 April 2024
 

src/main/kotlin/com/jetbrains/snakecharm/lang/parser/SmkStatementParsing.kt

@@ -180,20 +180,25 @@ class SmkStatementParsing(
         }
 
         // Other case: `rule` / `checkpoint` / etc.
+        var nameIdentifierSeen = false
         if (atToken(PyTokenTypes.IDENTIFIER)) {
             // rule name
             //val ruleNameMarker: PsiBuilder.Marker = myBuilder.mark()
             nextToken()
+            nameIdentifierSeen = true
         }
 
         // XXX at the moment we continue parsing rule even if colon missed, probably better
         // XXX to drop rule and scroll up to next STATEMENT_BREAK/RULE/CHECKPOINT/other toplevel keyword or eof()
-        checkMatches(PyTokenTypes.COLON,
-            "${
+        checkMatches(
+            PyTokenTypes.COLON,
+            if (nameIdentifierSeen) {
+                "':' expected"
+            } else {
                 section.name.replaceFirstChar {
                     if (it.isLowerCase()) it.titlecase(Locale.getDefault()) else it.toString()
-                }
-            } name identifier or ':' expected"
+                } + " name identifier or ':' expected"
+            }
         ) // bundle
 
         val ruleStatements = myBuilder.mark()

testData/psi/ModuleIncomplete.txt

@@ -11,7 +11,7 @@ SnakemakeFile: ModuleIncomplete.smk
     PsiElement(Py:MODULE_KEYWORD)('module')
     PsiWhiteSpace(' ')
     PsiElement(Py:IDENTIFIER)('z')
-    PsiErrorElement:Module name identifier or ':' expected
+    PsiErrorElement:':' expected
       <empty list>
     PyStatementList
       PsiErrorElement:Indent expected

testData/psi/RuleIncomplete2.txt

@@ -3,7 +3,7 @@ SnakemakeFile: RuleIncomplete2.smk
     PsiElement(Py:RULE_KEYWORD)('rule')
     PsiWhiteSpace(' ')
     PsiElement(Py:IDENTIFIER)('foo')
-    PsiErrorElement:Rule name identifier or ':' expected
+    PsiErrorElement:':' expected
       <empty list>
     PyStatementList
       <empty list>