TypeScriptToLua · Perryvw · May 30, 2022 · May 7, 2022 · May 7, 2022 · May 7, 2022
diff --git a/src/transformation/utils/lua-ast.ts b/src/transformation/utils/lua-ast.ts
@@ -202,6 +202,8 @@ export function createLocalOrExportedOrGlobalDeclaration(
         }
     }
 
+    setJSDocComments(context, tsOriginal, declaration, assignment);
+
     if (declaration && assignment) {
         return [declaration, assignment];
     } else if (declaration) {
@@ -213,6 +215,103 @@ export function createLocalOrExportedOrGlobalDeclaration(
     }
 }
 
+/**
+ * Apply JSDoc comments to the newly-created Lua statement, if present.
+ * https://stackoverflow.com/questions/47429792/is-it-possible-to-get-comments-as-nodes-in-the-ast-using-the-typescript-compiler
+ */
+function setJSDocComments(
+    context: TransformationContext,
+    tsOriginal: ts.Node | undefined,
+    declaration: lua.VariableDeclarationStatement | undefined,
+    assignment: lua.AssignmentStatement | undefined
+) {
+    // Respect the vanilla TypeScript option of "removeComments":
+    // https://www.typescriptlang.org/tsconfig#removeComments
+    if (context.options.removeComments) {
+        return;
+    }
+
+    const docCommentArray = getJSDocCommentFromTSNode(context, tsOriginal);
+    if (docCommentArray === undefined) {
+        return;
+    }
+
+    if (declaration && assignment) {
+        declaration.leadingComments = docCommentArray;
+    } else if (declaration) {
+        declaration.leadingComments = docCommentArray;
+    } else if (assignment) {
+        assignment.leadingComments = docCommentArray;
+    }
+}
+
+function getJSDocCommentFromTSNode(
+    context: TransformationContext,
+    tsOriginal: ts.Node | undefined
+): string[] | undefined {
+    if (tsOriginal === undefined) {
+        return undefined;
+    }
+
+    // The "name" property is only on a subset of node types; we want to be permissive and get the
+    // comments from as many nodes as possible.
+    const node = tsOriginal as any;
+    if (node.name === undefined) {
+        return undefined;
+    }
+
+    const symbol = context.checker.getSymbolAtLocation(node.name);
+    if (symbol === undefined) {
+        return undefined;
+    }
+
+    // The TypeScript compiler separates JSDoc comments into the "documentation comment" and the
+    // "tags". The former is conventionally at the top of the comment, and the bottom is
+    // conventionally at the bottom. We need to get both from the TypeScript API and then combine
+    // them into one block of text.
+    const docCommentArray = symbol.getDocumentationComment(context.checker);
+    const docCommentText = ts.displayPartsToString(docCommentArray).trim();
+
+    const jsDocTagInfoArray = symbol.getJsDocTags(context.checker);
+    const jsDocTagsTextLines = jsDocTagInfoArray.map(jsDocTagInfo => {
+        let text = "@" + jsDocTagInfo.name;
+        if (jsDocTagInfo.text !== undefined) {
+            const tagDescriptionTextArray = jsDocTagInfo.text
+                .filter(symbolDisplayPart => symbolDisplayPart.text.trim() !== "")
+                .map(symbolDisplayPart => symbolDisplayPart.text.trim());
+            const tagDescriptionText = tagDescriptionTextArray.join(" ");
+            text += " " + tagDescriptionText;
+        }
+        return text;
+    });
+    const jsDocTagsText = jsDocTagsTextLines.join("\n");
+
+    const combined = (docCommentText + "\n\n" + jsDocTagsText).trim();
+    if (combined === "") {
+        return undefined;
+    }
+
+    // By default, TSTL will display comments immediately next to the "--" characters. We can make
+    // the comments look better if we separate them by a space (similar to what Prettier does in
+    // JavaScript/TypeScript).
+    const linesWithoutSpace = combined.split("\n");
+    const lines = linesWithoutSpace.map(line => ` ${line}`);
+
+    // We want to JSDoc comments to map on to LDoc comments:
+    // https://stevedonovan.github.io/ldoc/manual/doc.md.html
+    // LDoc comments require that the first line starts with three hyphens.
+    // Thus, need to add a hyphen to the first line.
+    const firstLine = lines[0];
+    if (firstLine.startsWith(" @")) {
+        lines.unshift("-");
+    } else {
+        lines.shift();
+        lines.unshift("-" + firstLine);
+    }
+
+    return lines;
+}
+
 export const createNaN = (tsOriginal?: ts.Node) =>
     lua.createBinaryExpression(
         lua.createNumericLiteral(0),

diff --git a/test/unit/__snapshots__/comments.spec.ts.snap b/test/unit/__snapshots__/comments.spec.ts.snap
@@ -0,0 +1,50 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`JSDoc is copied on a function with tags: code 1`] = `
+"--- This is a function comment.
+-- It has multiple lines.
+-- 
+-- @param arg1 This is the first argument.
+-- @param arg2 This is the second argument.
+-- @returns A very powerful string.
+function foo(self, arg1, arg2)
+    return \\"bar\\"
+end"
+`;
+
+exports[`JSDoc is copied on a function with tags: diagnostics 1`] = `""`;
+
+exports[`JSDoc is copied on a variable: code 1`] = `
+"--- This is a variable comment.
+foo = 123"
+`;
+
+exports[`JSDoc is copied on a variable: diagnostics 1`] = `""`;
+
+exports[`Multi-line JSDoc with one block is copied on a function: code 1`] = `
+"--- This is a function comment.
+-- It has more than one line.
+function foo(self)
+end"
+`;
+
+exports[`Multi-line JSDoc with one block is copied on a function: diagnostics 1`] = `""`;
+
+exports[`Multi-line JSDoc with two blocks is copied on a function: code 1`] = `
+"--- This is a function comment.
+-- It has more than one line.
+-- 
+-- It also has more than one block.
+function foo(self)
+end"
+`;
+
+exports[`Multi-line JSDoc with two blocks is copied on a function: diagnostics 1`] = `""`;
+
+exports[`Single-line JSDoc is copied on a function: code 1`] = `
+"--- This is a function comment.
+function foo(self)
+end"
+`;
+
+exports[`Single-line JSDoc is copied on a function: diagnostics 1`] = `""`;
diff --git a/test/unit/__snapshots__/optionalChaining.spec.ts.snap b/test/unit/__snapshots__/optionalChaining.spec.ts.snap
@@ -32,9 +32,17 @@ exports[`Unsupported optional chains Builtin prototype method: diagnostics 1`] =
 exports[`Unsupported optional chains Compile members only: code 1`] = `
 "local ____exports = {}
 function ____exports.__main(self)
+    ---
+    -- @compileMembersOnly
     local A = 0
+    ---
+    -- @compileMembersOnly
     local B = 2
+    ---
+    -- @compileMembersOnly
     local C = 3
+    ---
+    -- @compileMembersOnly
     local D = \\"D\\"
     local ____TestEnum_B_0 = TestEnum
     if ____TestEnum_B_0 ~= nil then

diff --git a/test/unit/annotations/__snapshots__/customConstructor.spec.ts.snap b/test/unit/annotations/__snapshots__/customConstructor.spec.ts.snap
@@ -6,6 +6,8 @@ local __TS__Class = ____lualib.__TS__Class
 local __TS__New = ____lualib.__TS__New
 local ____exports = {}
 function ____exports.__main(self)
+    ---
+    -- @customConstructor
     local Point2D = __TS__Class()
     Point2D.name = \\"Point2D\\"
     function Point2D.prototype.____constructor(self)

diff --git a/test/unit/annotations/__snapshots__/deprecated.spec.ts.snap b/test/unit/annotations/__snapshots__/deprecated.spec.ts.snap
@@ -42,6 +42,8 @@ exports[`extension removed: code 1`] = `
 "local ____lualib = require(\\"lualib_bundle\\")
 local __TS__Class = ____lualib.__TS__Class
 local __TS__ClassExtends = ____lualib.__TS__ClassExtends
+---
+-- @extension
 B = __TS__Class()
 B.name = \\"B\\"
 __TS__ClassExtends(B, A)"
@@ -51,6 +53,8 @@ exports[`extension removed: code 2`] = `
 "local ____lualib = require(\\"lualib_bundle\\")
 local __TS__Class = ____lualib.__TS__Class
 local __TS__ClassExtends = ____lualib.__TS__ClassExtends
+---
+-- @metaExtension
 B = __TS__Class()
 B.name = \\"B\\"
 __TS__ClassExtends(B, A)"
@@ -108,6 +112,8 @@ exports[`pureAbstract removed: diagnostics 1`] = `"main.ts(4,22): error TSTL: '@
 exports[`tuplereturn lambda: code 1`] = `
 "local ____exports = {}
 function ____exports.__main(self)
+    ---
+    -- @tupleReturn
     local function f()
         return {3, 4}
     end
@@ -120,6 +126,8 @@ exports[`tuplereturn lambda: diagnostics 1`] = `"main.ts(2,39): error TSTL: '@tu
 exports[`tuplereturn removed on function declaration: code 1`] = `
 "local ____exports = {}
 function ____exports.__main(self)
+    ---
+    -- @tupleReturn
     local function tuple(self)
         return {3, 5, 1}
     end
@@ -132,6 +140,8 @@ exports[`tuplereturn removed on function declaration: diagnostics 1`] = `"main.t
 exports[`tuplereturn removed: code 1`] = `
 "local ____exports = {}
 function ____exports.__main(self)
+    ---
+    -- @tupleReturn
     local function tuple(self)
         return {3, 5, 1}
     end

diff --git a/test/unit/annotations/deprecated.spec.ts b/test/unit/annotations/deprecated.spec.ts
@@ -4,14 +4,14 @@ import * as util from "../../util";
 test.each(["extension", "metaExtension"])("extension removed", extensionType => {
     util.testModule`
         declare class A {}
-        /** @${extensionType} **/
+        /** @${extensionType} */
         class B extends A {}
     `.expectDiagnosticsToMatchSnapshot([annotationRemoved.code]);
 });
 
 test("phantom removed", () => {
     util.testModule`
-        /** @phantom **/
+        /** @phantom */
         namespace A {
             function nsMember() {}
         }

diff --git a/test/unit/comments.spec.ts b/test/unit/comments.spec.ts
@@ -0,0 +1,95 @@
+import * as util from "../util";
+
+test("Single-line JSDoc is copied on a function", () => {
+    const builder = util.testModule`
+        /** This is a function comment. */
+        function foo() {}
+    `
+        .expectToHaveNoDiagnostics()
+        .expectDiagnosticsToMatchSnapshot();
+
+    const transpiledFile = builder.getLuaResult().transpiledFiles[0];
+    expect(transpiledFile).toBeDefined();
+    const { lua } = transpiledFile;
+    expect(lua).toBeDefined();
+    expect(lua).toContain("This is a function comment.");
+});
+
+test("Multi-line JSDoc with one block is copied on a function", () => {
+    const builder = util.testModule`
+        /**
+         * This is a function comment.
+         * It has more than one line.
+         */
+        function foo() {}
+    `
+        .expectToHaveNoDiagnostics()
+        .expectDiagnosticsToMatchSnapshot();
+
+    const transpiledFile = builder.getLuaResult().transpiledFiles[0];
+    expect(transpiledFile).toBeDefined();
+    const { lua } = transpiledFile;
+    expect(lua).toBeDefined();
+    expect(lua).toContain("It has more than one line.");
+});
+
+test("Multi-line JSDoc with two blocks is copied on a function", () => {
+    const builder = util.testModule`
+        /**
+         * This is a function comment.
+         * It has more than one line.
+         *
+         * It also has more than one block.
+         */
+        function foo() {}
+    `
+        .expectToHaveNoDiagnostics()
+        .expectDiagnosticsToMatchSnapshot();
+
+    const transpiledFile = builder.getLuaResult().transpiledFiles[0];
+    expect(transpiledFile).toBeDefined();
+    const { lua } = transpiledFile;
+    expect(lua).toBeDefined();
+    expect(lua).toContain("It also has more than one block.");
+});
+
+test("JSDoc is copied on a function with tags", () => {
+    const builder = util.testModule`
+        /**
+         * This is a function comment.
+         * It has multiple lines.
+         *
+         * @param arg1 This is the first argument.
+         * @param arg2 This is the second argument.
+         * @returns A very powerful string.
+         */
+        function foo(arg1: boolean, arg2: number): string {
+            return "bar";
+        }
+    `
+        .expectToHaveNoDiagnostics()
+        .expectDiagnosticsToMatchSnapshot();
+
+    const transpiledFile = builder.getLuaResult().transpiledFiles[0];
+    expect(transpiledFile).toBeDefined();
+    const { lua } = transpiledFile;
+    expect(lua).toBeDefined();
+    expect(lua).toContain("This is the first argument.");
+    expect(lua).toContain("This is the second argument.");
+    expect(lua).toContain("A very powerful string.");
+});
+
+test("JSDoc is copied on a variable", () => {
+    const builder = util.testModule`
+        /** This is a variable comment. */
+        const foo = 123;
+    `
+        .expectToHaveNoDiagnostics()
+        .expectDiagnosticsToMatchSnapshot();
+
+    const transpiledFile = builder.getLuaResult().transpiledFiles[0];
+    expect(transpiledFile).toBeDefined();
+    const { lua } = transpiledFile;
+    expect(lua).toBeDefined();
+    expect(lua).toContain("This is a variable comment.");
+});