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Implement function.length (#889)
* Implement `function.length` * Add diagnostic on Lua 5.1 target * Add changelog * Remove outdated snapshots
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‎CHANGELOG.md‎

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@@ -1,5 +1,9 @@
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# Changelog
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## Unreleased
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- `Function.length` is supported now
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## 0.34.0
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- Added new `"luaTarget"` option value - `"universal"`. Choosing this target makes TypeScriptToLua generate code compatible with all supported Lua targets.

‎src/transformation/builtins/function.ts‎

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@@ -1,6 +1,8 @@
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import * as ts from "typescript";
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import { LuaTarget } from "../../CompilerOptions";
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import * as lua from "../../LuaAST";
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import { TransformationContext } from "../context";
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import { unsupportedProperty, unsupportedSelfFunctionConversion } from "../utils/diagnostics";
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import { unsupportedForTarget, unsupportedProperty, unsupportedSelfFunctionConversion } from "../utils/diagnostics";
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import { ContextType, getFunctionContextType } from "../utils/function-context";
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import { createUnpackCall } from "../utils/lua-ast";
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import { LuaLibFeature, transformLuaLibFunction } from "../utils/lualib";
@@ -35,3 +37,31 @@ export function transformFunctionPrototypeCall(
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context.diagnostics.push(unsupportedProperty(expression.name, "function", expressionName));
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}
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}
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export function transformFunctionProperty(
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context: TransformationContext,
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node: ts.PropertyAccessExpression
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): lua.Expression | undefined {
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switch (node.name.text) {
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case "length":
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if (context.luaTarget === LuaTarget.Lua51 || context.luaTarget === LuaTarget.Universal) {
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context.diagnostics.push(unsupportedForTarget(node, "function.length", LuaTarget.Lua51));
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}
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// debug.getinfo(fn)
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const getInfoCall = lua.createCallExpression(
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lua.createTableIndexExpression(lua.createIdentifier("debug"), lua.createStringLiteral("getinfo")),
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[context.transformExpression(node.expression)]
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);
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const nparams = lua.createTableIndexExpression(getInfoCall, lua.createStringLiteral("nparams"));
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const contextType = getFunctionContextType(context, context.checker.getTypeAtLocation(node.expression));
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return contextType === ContextType.NonVoid
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? lua.createBinaryExpression(nparams, lua.createNumericLiteral(1), lua.SyntaxKind.SubtractionOperator)
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: nparams;
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default:
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context.diagnostics.push(unsupportedProperty(node.name, "function", node.name.text));
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}
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}

‎src/transformation/builtins/index.ts‎

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@@ -16,7 +16,7 @@ import { PropertyCallExpression } from "../visitors/call";
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import { checkForLuaLibType } from "../visitors/class/new";
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import { transformArrayProperty, transformArrayPrototypeCall } from "./array";
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import { transformConsoleCall } from "./console";
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import { transformFunctionPrototypeCall } from "./function";
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import { transformFunctionPrototypeCall, transformFunctionProperty } from "./function";
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import { transformGlobalCall } from "./global";
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import { transformMathCall, transformMathProperty } from "./math";
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import { transformNumberConstructorCall, transformNumberPrototypeCall } from "./number";
@@ -38,6 +38,10 @@ export function transformBuiltinPropertyAccessExpression(
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return transformArrayProperty(context, node);
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}
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if (isFunctionType(context, ownerType)) {
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return transformFunctionProperty(context, node);
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}
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if (ts.isIdentifier(node.expression) && isStandardLibraryType(context, ownerType, undefined)) {
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switch (node.expression.text) {
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case "Math":

‎test/unit/functions/__snapshots__/functions.spec.ts.snap‎

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// Jest Snapshot v1, https://goo.gl/fbAQLP
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exports[`function.length unsupported ("5.1"): code 1`] = `
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"local ____exports = {}
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function ____exports.__main(self)
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local function fn(self)
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end
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return debug.getinfo(fn).nparams - 1
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end
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return ____exports"
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`;
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exports[`function.length unsupported ("5.1"): diagnostics 1`] = `"main.ts(3,16): error TSTL: function.length is/are not supported for target Lua 5.1."`;
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exports[`function.length unsupported ("universal"): code 1`] = `
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"local ____exports = {}
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function ____exports.__main(self)
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local function fn(self)
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end
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return debug.getinfo(fn).nparams - 1
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end
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return ____exports"
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`;
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exports[`function.length unsupported ("universal"): diagnostics 1`] = `"main.ts(3,16): error TSTL: function.length is/are not supported for target Lua 5.1."`;
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exports[`missing declaration name: code 1`] = `
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"function ____(self)
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end"

‎test/unit/functions/functions.spec.ts‎

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@@ -1,4 +1,6 @@
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import * as tstl from "../../../src";
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import * as util from "../../util";
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import { unsupportedForTarget } from "../../../src/transformation/utils/diagnostics";
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test("Arrow Function Expression", () => {
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util.testFunction`
@@ -185,6 +187,31 @@ test("Function call", () => {
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`.expectToMatchJsResult();
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});
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test.each([
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"function fn() {}",
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"function fn(x, y, z) {}",
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"function fn(x, y, z, ...args) {}",
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"function fn(...args) {}",
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"function fn(this: void) {}",
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"function fn(this: void, x, y, z) {}",
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"function fnReference(x, y, z) {} const fn = fnReference;",
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"const wrap = (fn: (...args: any[]) => any) => (...args: any[]) => fn(...args); const fn = wrap((x, y, z) => {});",
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])("function.length (%p)", declaration => {
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util.testFunction`
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${declaration}
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return fn.length;
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`.expectToMatchJsResult();
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});
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test.each([tstl.LuaTarget.Lua51, tstl.LuaTarget.Universal])("function.length unsupported (%p)", luaTarget => {
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util.testFunction`
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function fn() {}
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return fn.length;
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`
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.setOptions({ luaTarget })
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.expectDiagnosticsToMatchSnapshot([unsupportedForTarget.code]);
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});
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test("Recursive function definition", () => {
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util.testFunction`
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function f() { return typeof f; };

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