Add icons, diagnostics, completions & snippets

Add a dedicated Bison/Flex file icon theme and SVG icons, and register it in package.json to provide distinct icons for .y/.l files. Expand CHANGELOG and README with detailed diagnostics, screenshots, and a corrected test path. Enhance language server completions: %include file path suggestions, %skeleton and %define api.value.type values, and improved Flex abbreviation completions and context handling. Add many new Bison and Flex snippets (GLR skeleton, error recovery, union, numeric/identifier handlers, nested comment handler) to improve editor productivity.

Author: theodevelop

CHANGELOG.md

@@ -13,8 +13,25 @@ All notable changes to the **Bison/Flex Language Support** extension will be doc
   - Start condition highlighting (`<SC_NAME>`)
   - Abbreviation reference highlighting (`{name}`)
 - **Real-time diagnostics**
-  - Bison: undeclared tokens, orphan `%type` declarations, missing `%%`, unclosed blocks
-  - Flex: undefined start conditions, undefined abbreviations, missing `%%`, unclosed blocks
+  - Bison:
+    - Missing `%%` section separator (Error)
+    - Unknown/invalid directive — e.g. `%prout` (Error)
+    - Token used in grammar rules but not declared with `%token` (Warning)
+    - `%type` declared for a non-terminal that has no rule (Warning)
+    - Rule missing `%type` declaration when `api.value.type=variant` is active (Info)
+    - Unclosed `%{ %}` code block (Error)
+    - Unused grammar rules — not reachable from the start symbol (Warning)
+    - Unused tokens — declared with `%token` but never referenced in rules (Warning)
+    - Shift/reduce conflict heuristic — same terminal appears in two or more alternatives of a rule (Warning)
+  - Flex:
+    - Missing `%%` section separator (Error)
+    - Unknown/invalid directive — e.g. `%woops` (Error)
+    - Undefined start condition used in a rule (`<SC>` not declared with `%x`/`%s`) (Error)
+    - Undefined abbreviation referenced in a pattern (`{name}` not in definitions section) (Warning)
+    - Start condition declared but never used in any rule (Info)
+    - Abbreviation declared but never referenced in any pattern (Info)
+    - Unclosed `%{ %}` code block (Error)
+    - Inaccessible rule — catch-all pattern before a specific pattern, or duplicate pattern (Warning)
 - **Autocompletion**
   - 30+ Bison directives with documentation
   - 20+ Flex `%option` values
@@ -32,3 +49,6 @@ All notable changes to the **Bison/Flex Language Support** extension will be doc
   - 12 Flex snippets (scanner skeleton, RE-flex skeleton, comment/string handlers)
 - **Language configuration**
   - Bracket matching, auto-closing pairs, comment toggling, folding
+- **File icon theme** (`bison-flex-icons`)
+  - Distinct orange "B" icon for Bison files (`.y`, `.yy`, `.ypp`, `.bison`)
+  - Distinct blue "F" icon for Flex files (`.l`, `.ll`, `.lex`, `.flex`)

README.md

@@ -75,6 +75,25 @@ Ready-to-use templates to speed up your workflow:
 
 ---
 
+## Screenshots
+
+### Syntax Highlighting
+![Syntax highlighting with section-aware coloring and embedded C/C++](images/syntax-highlighting.png)
+
+### Hover Documentation
+![Inline hover docs for Bison directives and Flex options](images/hover-docs.png)
+
+### Autocompletion
+![Context-aware completions for directives, tokens, and semantic values](images/autocompletion.png)
+
+### Diagnostics
+![Real-time error and warning markers for undeclared tokens, missing separators, and more](images/diagnostics.png)
+
+### Snippets
+![Code snippet expansion for grammar skeletons and rule templates](images/snippets.png)
+
+---
+
 ## Supported File Types
 
 | Language | Extensions | Aliases |
@@ -144,7 +163,7 @@ Contributions are welcome! Here's how to get started:
 ### Running Tests
 
 ```bash
-npx ts-node --project server/tsconfig.json test-parsers.ts
+npx ts-node --project server/tsconfig.json tests/test-parsers.ts
 ```
 
 ### Building for Production

bison-flex-icon-theme.json

@@ -0,0 +1,21 @@
+{
+  "iconDefinitions": {
+    "_bison": {
+      "iconPath": "./images/bison-icon.svg"
+    },
+    "_flex": {
+      "iconPath": "./images/flex-icon.svg"
+    }
+  },
+  "fileExtensions": {
+    "y":     "_bison",
+    "yy":    "_bison",
+    "ypp":   "_bison",
+    "bison": "_bison",
+    "l":     "_flex",
+    "ll":    "_flex",
+    "lex":   "_flex",
+    "flex":  "_flex"
+  },
+  "fileNames": {}
+}

images/bison-icon.svg

@@ -97,6 +97,13 @@
         "path": "./snippets/flex.json"
       }
     ],
+    "iconThemes": [
+      {
+        "id": "bison-flex-icons",
+        "label": "Bison/Flex File Icons",
+        "path": "./bison-flex-icon-theme.json"
+      }
+    ],
     "configuration": {
       "title": "Bison & Flex",
       "properties": {

images/flex-icon.svg

@@ -6,6 +6,9 @@ import {
   TextDocument,
 } from 'vscode-languageserver';
 import { BisonDocument, FlexDocument, DocumentModel, isBisonDocument } from '../parser/types';
+import { fileURLToPath } from 'url';
+import * as fs from 'fs';
+import * as path from 'path';
 import {
   bisonDirectiveDocs,
   bisonDefineDocs,
@@ -25,7 +28,7 @@ export function getCompletions(
   const linePrefix = lineText.substring(0, position.character);
 
   if (isBisonDocument(doc)) {
-    return getBisonCompletions(doc, linePrefix, position, text);
+    return getBisonCompletions(doc, linePrefix, position, text, textDoc);
   } else {
     return getFlexCompletions(doc, linePrefix, position, text);
   }
@@ -35,10 +38,78 @@ function getBisonCompletions(
   doc: BisonDocument,
   linePrefix: string,
   position: Position,
-  _text: string
+  _text: string,
+  textDoc: TextDocument
 ): CompletionItem[] {
   const items: CompletionItem[] = [];
 
+  // T1. %include file completions
+  if (linePrefix.match(/%include\s+["'<][^"'<>]*$/)) {
+    const match = linePrefix.match(/%include\s+["'<](.*)$/);
+    const partial = match ? match[1] : '';
+    try {
+      const fileDir = path.dirname(fileURLToPath(textDoc.uri));
+      const targetDir = partial.includes('/') || partial.includes(path.sep)
+        ? path.join(fileDir, path.dirname(partial))
+        : fileDir;
+      const entries = fs.readdirSync(targetDir, { withFileTypes: true });
+      return entries.map(entry => ({
+        label: entry.name,
+        kind: entry.isDirectory() ? CompletionItemKind.Folder : CompletionItemKind.File,
+        detail: entry.isDirectory() ? 'Directory' : 'File',
+        sortText: (entry.isDirectory() ? '0' : '1') + entry.name,
+      }));
+    } catch {
+      return [];
+    }
+  }
+
+  // T3. %skeleton value completions
+  if (linePrefix.match(/%skeleton\s+\S*$/)) {
+    return [
+      { label: '"lalr1.cc"', kind: CompletionItemKind.Value, detail: 'C++ LALR(1) parser (default for C++)', sortText: '0' },
+      { label: '"glr.cc"',   kind: CompletionItemKind.Value, detail: 'C++ GLR parser',                       sortText: '1' },
+      { label: '"lalr1.c"',  kind: CompletionItemKind.Value, detail: 'C LALR(1) parser',                     sortText: '2' },
+      { label: '"glr.c"',    kind: CompletionItemKind.Value, detail: 'C GLR parser',                         sortText: '3' },
+      { label: '"location.cc"', kind: CompletionItemKind.Value, detail: 'Location tracking only',            sortText: '4' },
+    ];
+  }
+
+  // T2. %define api.value.type value completions
+  if (linePrefix.match(/%define\s+api\.value\.type\s+\S*$/)) {
+    return [
+      {
+        label: 'variant',
+        kind: CompletionItemKind.Value,
+        detail: 'C++ std::variant (Bison ≥ 3.2, requires C++17)',
+        documentation: { kind: 'markdown', value: 'Each semantic value is stored as `std::variant`. Requires `%language "c++"` and a C++17 compiler.' },
+        sortText: '0',
+      },
+      {
+        label: 'union',
+        kind: CompletionItemKind.Value,
+        detail: 'C union (classic default)',
+        documentation: { kind: 'markdown', value: 'Uses the `YYSTYPE` union. Compatible with C and older C++ Bison grammars.' },
+        sortText: '1',
+      },
+      {
+        label: 'union-directive',
+        kind: CompletionItemKind.Value,
+        detail: 'Union defined by %union directive',
+        documentation: { kind: 'markdown', value: 'Use a union body declared with `%union { ... }`.' },
+        sortText: '2',
+      },
+      {
+        label: 'std::variant<int, std::string>',
+        kind: CompletionItemKind.Value,
+        detail: 'Explicit std::variant type list',
+        insertText: 'std::variant<${1:int, std::string}>',
+        insertTextFormat: InsertTextFormat.Snippet,
+        sortText: '3',
+      },
+    ];
+  }
+
   // 1. Directive completions (after %)
   if (linePrefix.match(/%\w*$/) && !linePrefix.match(/%%.*/)) {
     for (const [name, entry] of bisonDirectiveDocs) {
@@ -232,8 +303,9 @@ function getFlexCompletions(
     return items;
   }
 
-  // 4. Abbreviation completions (after {)
-  if (linePrefix.match(/\{[a-zA-Z_]*$/)) {
+  // T4. Abbreviation completions in rule patterns (after {, in rules section only)
+  const isInFlexRules = doc.separators.length > 0 && position.line > doc.separators[0];
+  if (isInFlexRules && linePrefix.match(/\{[a-zA-Z_]*$/)) {
     for (const [name, abbr] of doc.abbreviations) {
       items.push({
         label: name,
@@ -243,7 +315,21 @@ function getFlexCompletions(
         sortText: '0' + name,
       });
     }
-    return items;
+    if (items.length > 0) return items;
+  }
+
+  // Abbreviation completions in definitions section (nested abbreviations)
+  if (!isInFlexRules && linePrefix.match(/\{[a-zA-Z_]*$/)) {
+    for (const [name, abbr] of doc.abbreviations) {
+      items.push({
+        label: name,
+        kind: CompletionItemKind.Variable,
+        detail: `Abbreviation: ${abbr.pattern}`,
+        insertText: name + '}',
+        sortText: '0' + name,
+      });
+    }
+    if (items.length > 0) return items;
   }
 
   // 5. Snippets

package.json

@@ -157,5 +157,86 @@
     "body": [
       "%prec ${1:TOKEN}"
     ]
+  },
+
+  "GLR Grammar Skeleton": {
+    "prefix": "glr-skeleton",
+    "description": "Complete Bison GLR grammar with %glr-parser, %define parse.lac, and ambiguous rule example",
+    "body": [
+      "// -*- C++ -*-",
+      "%require \"3.8\"",
+      "%glr-parser",
+      "%language \"c++\"",
+      "",
+      "%define api.namespace {${1:parse}}",
+      "%define api.parser.class {${2:parser}}",
+      "%define api.value.type variant",
+      "%define api.token.constructor",
+      "%define parse.error verbose",
+      "%define parse.lac full",
+      "",
+      "%defines",
+      "%locations",
+      "",
+      "%code requires",
+      "{",
+      "  #include <string>",
+      "  $3",
+      "}",
+      "",
+      "%token <int>         INT    \"integer\"",
+      "%token <std::string> ID     \"identifier\"",
+      "%token               PLUS   \"+\"",
+      "",
+      "%type <${4:int}> ${5:expr}",
+      "",
+      "%start ${6:program}",
+      "",
+      "%%",
+      "",
+      "$6:",
+      "  $5 { $$ = $1; }",
+      ";",
+      "",
+      "$5:",
+      "  INT             { $$ = $1; }",
+      "| $5 \"+\" $5     { $$ = $1 + $3; }",
+      ";",
+      "",
+      "%%",
+      "",
+      "void",
+      "${1}::${2}::error(const location_type& l, const std::string& m)",
+      "{",
+      "  std::cerr << l << \": \" << m << std::endl;",
+      "}"
+    ]
+  },
+
+  "Error Recovery Rule": {
+    "prefix": "error-recovery",
+    "description": "Grammar rule with error token for panic-mode error recovery",
+    "body": [
+      "${1:statement}:",
+      "  ${2:expr} '${3:;}' { $$ = $1; }",
+      "| error '${3}' { yyerrok; $$ = ${4:0}; }",
+      ";"
+    ]
+  },
+
+  "Union Declaration": {
+    "prefix": "union-decl",
+    "description": "%union with common C types for YYSTYPE",
+    "body": [
+      "%union",
+      "{",
+      "  int           ival;   /* integer value  */",
+      "  double        dval;   /* float value    */",
+      "  char*         sval;   /* string value   */",
+      "  char          cval;   /* char value     */",
+      "  unsigned int  uval;   /* unsigned value */",
+      "  ${1:/* custom field */}",
+      "}"
+    ]
   }
 }