Fix for trailing comments in root node

fasttime · fasttime · commit 449e89426008 · 2023-03-20T19:47:55.000+01:00
diff --git a/lib/source-code/token-store/utils.js b/lib/source-code/token-store/utils.js
@@ -84,9 +84,9 @@ exports.getLastIndex = function getLastIndex(tokens, indexMap, endLoc) {
         const index = indexMap[endLoc - 1];
         const token = tokens[index];
 
-        // If the mapped index is out of bounds, the returned cursor index will point before the start of the tokens array.
+        // If the mapped index is out of bounds, the returned cursor index will point before the end of the tokens array.
         if (!token) {
-            return -1;
+            return tokens.length - 1;
         }
 
         /*
diff --git a/tests/fixtures/parsers/all-comments-parser.js b/tests/fixtures/parsers/all-comments-parser.js
@@ -0,0 +1,28 @@
+// Similar to the default parser, but considers leading and trailing comments to be part of the root node.
+// Some custom parsers like @typescript-eslint/parser behave in this way.
+
+const espree = require("espree");
+exports.parse = function(code, options) {
+    const ast = espree.parse(code, options);
+
+    if (ast.range && ast.comments && ast.comments.length > 0) {
+        const firstComment = ast.comments[0];
+        const lastComment = ast.comments[ast.comments.length - 1];
+
+        if (ast.range[0] > firstComment.range[0]) {
+            ast.range[0] = firstComment.range[0];
+            ast.start = firstComment.start;
+            if (ast.loc) {
+                ast.loc.start = firstComment.loc.start;
+            }
+        }
+        if (ast.range[1] < lastComment.range[1]) {
+            ast.range[1] = lastComment.range[1];
+            ast.end = lastComment.end;
+            if (ast.loc) {
+                ast.loc.end = lastComment.loc.end;
+            }
+        }
+    }
+    return ast;
+};
diff --git a/tests/lib/source-code/token-store.js b/tests/lib/source-code/token-store.js
@@ -654,6 +654,16 @@ describe("TokenStore", () => {
             assert.strictEqual(token.value, "c");
         });
 
+        it("should retrieve the first token if the root node contains a trailing comment", () => {
+            const parser = require("../../fixtures/parsers/all-comments-parser");
+            const code = "foo // comment";
+            const ast = parser.parse(code, { loc: true, range: true, tokens: true, comment: true });
+            const tokenStore = new TokenStore(ast.tokens, ast.comments);
+            const token = tokenStore.getFirstToken(ast);
+
+            assert.strictEqual(token, ast.tokens[0]);
+        });
+
         it("should return null if the source contains only comments", () => {
             const code = "// comment";
             const ast = espree.parse(code, { loc: true, range: true, tokens: true, comment: true });
@@ -863,6 +873,16 @@ describe("TokenStore", () => {
             assert.strictEqual(token.value, "b");
         });
 
+        it("should retrieve the last token if the root node contains a trailing comment", () => {
+            const parser = require("../../fixtures/parsers/all-comments-parser");
+            const code = "foo // comment";
+            const ast = parser.parse(code, { loc: true, range: true, tokens: true, comment: true });
+            const tokenStore = new TokenStore(ast.tokens, ast.comments);
+            const token = tokenStore.getLastToken(ast);
+
+            assert.strictEqual(token, ast.tokens[0]);
+        });
+
         it("should return null if the source contains only comments", () => {
             const code = "// comment";
             const ast = espree.parse(code, { loc: true, range: true, tokens: true, comment: true });
