TypeScriptToLua · Perryvw · Dec 8, 2019 · Dec 8, 2019 · Dec 8, 2019 · Dec 8, 2019
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -39,24 +39,24 @@
         "node": ">=8.5.0"
     },
     "dependencies": {
-        "resolve": "^1.11.0",
+        "resolve": "^1.13.1",
         "source-map": "^0.7.3",
-        "typescript": "^3.6.2"
+        "typescript": "^3.7.3"
     },
     "devDependencies": {
         "@types/fs-extra": "^8.0.1",
         "@types/glob": "^7.1.1",
-        "@types/jest": "^24.0.15",
-        "@types/node": "^11.13.14",
+        "@types/jest": "^24.0.23",
+        "@types/node": "^12.12.14",
         "@types/resolve": "0.0.8",
         "fengari": "^0.1.4",
         "fs-extra": "^8.1.0",
-        "javascript-stringify": "^2.0.0",
-        "jest": "^24.8.0",
-        "jest-circus": "^24.8.0",
-        "prettier": "^1.18.2",
-        "ts-jest": "^24.0.2",
-        "ts-node": "^7.0.1",
-        "tslint": "^5.17.0"
+        "javascript-stringify": "^2.0.1",
+        "jest": "^24.9.0",
+        "jest-circus": "^24.9.0",
+        "prettier": "^1.19.1",
+        "ts-jest": "^24.2.0",
+        "ts-node": "^8.5.4",
+        "tslint": "^5.20.1"
     }
 }
diff --git a/src/Emit.ts b/src/Emit.ts
@@ -19,7 +19,7 @@ export function emitTranspiledFiles(
     let { outDir, luaLibImport, luaBundle } = options;
 
     const rootDir = program.getCommonSourceDirectory();
-    outDir = outDir || rootDir;
+    outDir = outDir ?? rootDir;
 
     const files: OutputFile[] = [];
     for (const { fileName, lua, sourceMap, declaration, declarationMap } of transpiledFiles) {
@@ -54,7 +54,7 @@ export function emitTranspiledFiles(
             luaLibImport === LuaLibImportKind.Require ||
             luaLibImport === LuaLibImportKind.Always)
     ) {
-        const lualibRequired = files.some(f => f.text && f.text.includes(`require("lualib_bundle")`));
+        const lualibRequired = files.some(f => f.text?.includes(`require("lualib_bundle")`));
         if (lualibRequired) {
             if (lualibContent === undefined) {
                 const lualibBundle = emitHost.readFile(path.resolve(__dirname, "../dist/lualib/lualib_bundle.lua"));

diff --git a/src/LuaAST.ts b/src/LuaAST.ts
@@ -186,7 +186,7 @@ export function setParent(node: Node | Node[] | undefined, parent: Node): void {
 }
 
 function getSourcePosition(sourceNode: ts.Node): TextRange | undefined {
-    if (sourceNode !== undefined && sourceNode.getSourceFile() !== undefined && sourceNode.pos >= 0) {
+    if (sourceNode.getSourceFile() !== undefined && sourceNode.pos >= 0) {
         const { line, character } = ts.getLineAndCharacterOfPosition(
             sourceNode.getSourceFile(),
             sourceNode.pos + sourceNode.getLeadingTriviaWidth()
@@ -901,12 +901,7 @@ export type FunctionDefinition = (VariableDeclarationStatement | AssignmentState
 export function isFunctionDefinition(
     statement: VariableDeclarationStatement | AssignmentStatement
 ): statement is FunctionDefinition {
-    return (
-        statement.left.length === 1 &&
-        statement.right !== undefined &&
-        statement.right.length === 1 &&
-        isFunctionExpression(statement.right[0])
-    );
+    return statement.left.length === 1 && statement.right?.length === 1 && isFunctionExpression(statement.right[0]);
 }
 
 export type InlineFunctionExpression = FunctionExpression & {
@@ -915,8 +910,7 @@ export type InlineFunctionExpression = FunctionExpression & {
 
 export function isInlineFunctionExpression(expression: FunctionExpression): expression is InlineFunctionExpression {
     return (
-        expression.body.statements !== undefined &&
-        expression.body.statements.length === 1 &&
+        expression.body.statements?.length === 1 &&
         isReturnStatement(expression.body.statements[0]) &&
         (expression.body.statements[0] as ReturnStatement).expressions !== undefined &&
         (expression.flags & FunctionExpressionFlags.Inline) !== 0

diff --git a/src/LuaPrinter.ts b/src/LuaPrinter.ts
@@ -23,8 +23,7 @@ const escapeStringMap: Record<string, string> = {
     "\0": "\\0",
 };
 
-export const escapeString = (value: string) =>
-    `"${value.replace(escapeStringRegExp, char => escapeStringMap[char] || char)}"`;
+export const escapeString = (value: string) => `"${value.replace(escapeStringRegExp, char => escapeStringMap[char])}"`;
 
 /**
  * Checks that a name is valid for use in lua function declaration syntax:
@@ -198,7 +197,7 @@ export class LuaPrinter {
             header += `--[[ Generated with https://github.com/TypeScriptToLua/TypeScriptToLua ]]\n`;
         }
 
-        const luaLibImport = this.options.luaLibImport || LuaLibImportKind.Require;
+        const luaLibImport = this.options.luaLibImport ?? LuaLibImportKind.Require;
         if (
             luaLibImport === LuaLibImportKind.Always ||
             (luaLibImport === LuaLibImportKind.Require && luaLibFeatures.size > 0)
@@ -341,11 +340,21 @@ export class LuaPrinter {
             // Print all local functions as `local function foo()` instead of `local foo = function` to allow recursion
             chunks.push(this.printFunctionDefinition(statement));
         } else {
-            chunks.push(...this.joinChunks(", ", statement.left.map(e => this.printExpression(e))));
+            chunks.push(
+                ...this.joinChunks(
+                    ", ",
+                    statement.left.map(e => this.printExpression(e))
+                )
+            );
 
             if (statement.right) {
                 chunks.push(" = ");
-                chunks.push(...this.joinChunks(", ", statement.right.map(e => this.printExpression(e))));
+                chunks.push(
+                    ...this.joinChunks(
+                        ", ",
+                        statement.right.map(e => this.printExpression(e))
+                    )
+                );
             }
         }
 
@@ -369,9 +378,19 @@ export class LuaPrinter {
             }
         }
 
-        chunks.push(...this.joinChunks(", ", statement.left.map(e => this.printExpression(e))));
+        chunks.push(
+            ...this.joinChunks(
+                ", ",
+                statement.left.map(e => this.printExpression(e))
+            )
+        );
         chunks.push(" = ");
-        chunks.push(...this.joinChunks(", ", statement.right.map(e => this.printExpression(e))));
+        chunks.push(
+            ...this.joinChunks(
+                ", ",
+                statement.right.map(e => this.printExpression(e))
+            )
+        );
 
         return this.createSourceNode(statement, chunks);
     }
@@ -458,8 +477,14 @@ export class LuaPrinter {
     }
 
     public printForInStatement(statement: lua.ForInStatement): SourceNode {
-        const names = this.joinChunks(", ", statement.names.map(i => this.printIdentifier(i)));
-        const expressions = this.joinChunks(", ", statement.expressions.map(e => this.printExpression(e)));
+        const names = this.joinChunks(
+            ", ",
+            statement.names.map(i => this.printIdentifier(i))
+        );
+        const expressions = this.joinChunks(
+            ", ",
+            statement.expressions.map(e => this.printExpression(e))
+        );
 
         const chunks: SourceChunk[] = [];
 
@@ -488,7 +513,12 @@ export class LuaPrinter {
 
         const chunks: SourceChunk[] = [];
 
-        chunks.push(...this.joinChunks(", ", statement.expressions.map(e => this.printExpression(e))));
+        chunks.push(
+            ...this.joinChunks(
+                ", ",
+                statement.expressions.map(e => this.printExpression(e))
+            )
+        );
 
         return this.createSourceNode(statement, [this.indent(), "return ", ...chunks]);
     }
@@ -588,7 +618,10 @@ export class LuaPrinter {
             chunks.push(" ");
             const returnNode: SourceChunk[] = [
                 "return ",
-                ...this.joinChunks(", ", returnStatement.expressions.map(e => this.printExpression(e))),
+                ...this.joinChunks(
+                    ", ",
+                    returnStatement.expressions.map(e => this.printExpression(e))
+                ),
             ];
             chunks.push(this.createSourceNode(returnStatement, returnNode));
             chunks.push(this.createSourceNode(expression, " end"));
@@ -780,7 +813,12 @@ export class LuaPrinter {
         const chunks: SourceChunk[] = [];
 
         if (expressions.every(isSimpleExpression)) {
-            chunks.push(...this.joinChunks(", ", expressions.map(e => this.printExpression(e))));
+            chunks.push(
+                ...this.joinChunks(
+                    ", ",
+                    expressions.map(e => this.printExpression(e))
+                )
+            );
         } else {
             chunks.push("\n");
             this.pushIndent();

diff --git a/src/TSTransformers.ts b/src/TSTransformers.ts
@@ -20,8 +20,8 @@ export function getCustomTransformers(
     const transformersFromOptions = loadTransformersFromOptions(program, diagnostics);
 
     const afterDeclarations = [
-        ...(transformersFromOptions.afterDeclarations || []),
-        ...(customTransformers.afterDeclarations || []),
+        ...(transformersFromOptions.afterDeclarations ?? []),
+        ...(customTransformers.afterDeclarations ?? []),
     ];
 
     const options = program.getCompilerOptions() as CompilerOptions;
@@ -32,11 +32,11 @@ export function getCustomTransformers(
     return {
         afterDeclarations,
         before: [
-            ...(customTransformers.before || []),
-            ...(transformersFromOptions.before || []),
+            ...(customTransformers.before ?? []),
+            ...(transformersFromOptions.before ?? []),
 
-            ...(transformersFromOptions.after || []),
-            ...(customTransformers.after || []),
+            ...(transformersFromOptions.after ?? []),
+            ...(customTransformers.after ?? []),
             luaTransformer,
         ],
     };
@@ -197,7 +197,7 @@ function loadTransformer(
     } else {
         const isValidGroupTransformer =
             typeof transformer === "object" &&
-            (transformer.before || transformer.after || transformer.afterDeclarations);
+            (transformer.before ?? transformer.after ?? transformer.afterDeclarations) !== undefined;
 
         if (!isValidGroupTransformer) {
             return { error: diagnosticFactories.transformerShouldBeATsTransformerFactory(transform) };

diff --git a/src/bundle.ts b/src/bundle.ts
@@ -41,7 +41,7 @@ export function bundleTranspiledFiles(
     );
 
     // If any of the modules contains a require for lualib_bundle, add it to the module table.
-    const lualibRequired = transpiledFiles.some(f => f.lua && f.lua.includes(`require("lualib_bundle")`));
+    const lualibRequired = transpiledFiles.some(f => f.lua?.includes(`require("lualib_bundle")`));
     if (lualibRequired) {
         const lualibBundle = emitHost.readFile(path.resolve(__dirname, "../dist/lualib/lualib_bundle.lua"));
         moduleTableEntries.push(`["lualib_bundle"] = function() ${lualibBundle} end,\n`);

diff --git a/src/cli/information.ts b/src/cli/information.ts
@@ -19,7 +19,7 @@ export function getHelpString(): string {
 
     result += "Options:\n";
     for (const option of optionDeclarations) {
-        const aliasStrings = (option.aliases || []).map(a => "-" + a);
+        const aliasStrings = (option.aliases ?? []).map(a => "-" + a);
         const optionString = aliasStrings.concat(["--" + option.name]).join("|");
 
         const valuesHint = option.type === "enum" ? option.choices.join("|") : option.type;

diff --git a/src/transformation/builtins/index.ts b/src/transformation/builtins/index.ts
@@ -1,5 +1,6 @@
 import * as ts from "typescript";
 import * as lua from "../../LuaAST";
+import { assume } from "../../utils";
 import { TransformationContext } from "../context";
 import { importLuaLibFeature, LuaLibFeature } from "../utils/lualib";
 import { getIdentifierSymbolId } from "../utils/symbols";
@@ -60,8 +61,7 @@ export function transformBuiltinCallExpression(
         return;
     }
 
-    // TODO(TypeScript 3.7): assume
-    const propertyCall = node as PropertyCallExpression;
+    assume<PropertyCallExpression>(node);
 
     // If the function being called is of type owner.func, get the type of owner
     const ownerType = context.checker.getTypeAtLocation(node.expression.expression);
@@ -71,40 +71,40 @@ export function transformBuiltinCallExpression(
         const symbolName = symbol && symbol.name;
         switch (symbolName) {
             case "Console":
-                return transformConsoleCall(context, propertyCall);
+                return transformConsoleCall(context, node);
             case "Math":
-                return transformMathCall(context, propertyCall);
+                return transformMathCall(context, node);
             case "StringConstructor":
-                return transformStringConstructorCall(context, propertyCall);
+                return transformStringConstructorCall(context, node);
             case "ObjectConstructor":
-                return transformObjectConstructorCall(context, propertyCall);
+                return transformObjectConstructorCall(context, node);
             case "SymbolConstructor":
-                return transformSymbolConstructorCall(context, propertyCall);
+                return transformSymbolConstructorCall(context, node);
             case "NumberConstructor":
-                return transformNumberConstructorCall(context, propertyCall);
+                return transformNumberConstructorCall(context, node);
         }
     }
 
     if (isStringType(context, ownerType)) {
-        return transformStringPrototypeCall(context, propertyCall);
+        return transformStringPrototypeCall(context, node);
     }
 
     if (isNumberType(context, ownerType)) {
-        return transformNumberPrototypeCall(context, propertyCall);
+        return transformNumberPrototypeCall(context, node);
     }
 
     if (isArrayType(context, ownerType)) {
-        const result = transformArrayPrototypeCall(context, propertyCall);
+        const result = transformArrayPrototypeCall(context, node);
         if (result) {
             return result;
         }
     }
 
     if (isFunctionType(context, ownerType)) {
-        return transformFunctionPrototypeCall(context, propertyCall);
+        return transformFunctionPrototypeCall(context, node);
     }
 
-    const objectResult = transformObjectPrototypeCall(context, propertyCall);
+    const objectResult = transformObjectPrototypeCall(context, node);
     if (objectResult) {
         return objectResult;
     }

diff --git a/src/transformation/context/context.ts b/src/transformation/context/context.ts
@@ -23,25 +23,24 @@ export class TransformationContext {
     public readonly resolver: EmitResolver;
 
     public readonly options: CompilerOptions = this.program.getCompilerOptions();
-    public readonly luaTarget = this.options.luaTarget || LuaTarget.LuaJIT;
+    public readonly luaTarget = this.options.luaTarget ?? LuaTarget.LuaJIT;
     public readonly isModule = isFileModule(this.sourceFile);
     public readonly isStrict =
-        this.options.alwaysStrict !== undefined ||
-        (this.options.strict !== undefined && this.options.alwaysStrict !== false) ||
+        (this.options.alwaysStrict ?? this.options.strict) ||
         (this.isModule && this.options.target !== undefined && this.options.target >= ts.ScriptTarget.ES2015);
 
     public constructor(public program: ts.Program, public sourceFile: ts.SourceFile, private visitorMap: VisitorMap) {
         // Use `getParseTreeNode` to get original SourceFile node, before it was substituted by custom transformers.
         // It's required because otherwise `getEmitResolver` won't use cached diagnostics, produced in `emitWorker`
         // and would try to re-analyze the file, which would fail because of replaced nodes.
-        const originalSourceFile = ts.getParseTreeNode(sourceFile, ts.isSourceFile) || sourceFile;
+        const originalSourceFile = ts.getParseTreeNode(sourceFile, ts.isSourceFile) ?? sourceFile;
         this.resolver = this.checker.getEmitResolver(originalSourceFile);
     }
 
     private currentNodeVisitors: Array<ObjectVisitor<ts.Node>> = [];
     public transformNode(node: ts.Node): lua.Node[] {
         // TODO: Move to visitors?
-        if (node.modifiers && node.modifiers.some(modifier => modifier.kind === ts.SyntaxKind.DeclareKeyword)) {
+        if (node.modifiers?.some(modifier => modifier.kind === ts.SyntaxKind.DeclareKeyword)) {
             return [];
         }
 

diff --git a/src/transformation/index.ts b/src/transformation/index.ts
@@ -34,7 +34,7 @@ export function createVisitorMap(customVisitors: Visitors[]): VisitorMap {
     }
 
     for (const nodeVisitors of visitorMap.values()) {
-        nodeVisitors.sort((a, b) => (a.priority || 0) - (b.priority || 0));
+        nodeVisitors.sort((a, b) => (a.priority ?? 0) - (b.priority ?? 0));
     }
 
     return visitorMap;

diff --git a/src/transformation/utils/annotations.ts b/src/transformation/utils/annotations.ts
@@ -102,7 +102,7 @@ export function getFileAnnotations(sourceFile: ts.SourceFile): AnnotationsMap {
         // Manually collect jsDoc because `getJSDocTags` includes tags only from closest comment
         const jsDoc = sourceFile.statements[0].jsDoc;
         if (jsDoc) {
-            for (const tag of flatMap(jsDoc, x => x.tags || [])) {
+            for (const tag of flatMap(jsDoc, x => x.tags ?? [])) {
                 const tagName = tag.tagName.text;
                 const annotation = createAnnotation(tagName, tag.comment ? tag.comment.split(" ") : []);
                 if (annotation) {

diff --git a/src/transformation/utils/export.ts b/src/transformation/utils/export.ts
@@ -6,8 +6,8 @@ import { createExportsIdentifier } from "./lua-ast";
 import { getSymbolInfo } from "./symbols";
 import { findFirstNodeAbove, isFileModule } from "./typescript";
 
-export function hasDefaultExportModifier({ modifiers }: ts.Node): boolean {
-    return modifiers !== undefined && modifiers.some(modifier => modifier.kind === ts.SyntaxKind.DefaultKeyword);
+export function hasDefaultExportModifier(node: ts.Node): boolean {
+    return (node.modifiers ?? []).some(modifier => modifier.kind === ts.SyntaxKind.DefaultKeyword);
 }
 
 export const createDefaultExportIdentifier = (original: ts.Node): lua.Identifier =>

diff --git a/src/transformation/utils/function-context.ts b/src/transformation/utils/function-context.ts
@@ -129,7 +129,7 @@ function getSignatureDeclarations(
 
 export function getFunctionContextType(context: TransformationContext, type: ts.Type): ContextType {
     if (type.isTypeParameter()) {
-        type = type.getConstraint() || type;
+        type = type.getConstraint() ?? type;
     }
 
     if (type.isUnion()) {