KAS: try to type some things (#1449)

* make parser-generator ts

* make compare happy with types

* add return type for compare

* move index to ts

* undo that

* changeset

* respond to Jeremys feedback

.changeset/shy-scissors-type.md

@@ -0,0 +1,5 @@
+---
+"@khanacademy/kas": patch
+---
+
+Add some types to the KAS package

packages/kas/package.json

@@ -22,7 +22,7 @@
         "dist"
     ],
     "scripts": {
-        "gen:parsers": "node src/parser-generator.js",
+        "gen:parsers": "node src/parser-generator.ts",
         "test": "bash -c 'yarn --silent --cwd \"../..\" test ${@:0} $($([[ ${@: -1} = -* ]] || [[ ${@: -1} = bash ]]) && echo $PWD)'"
     },
     "dependencies": {

packages/kas/src/compare.js → packages/kas/src/compare.ts

@@ -1,33 +1,30 @@
-/* eslint-disable */
-import _ from "underscore";
+import type {CompareOptions, CompareResult, Expression} from "./types";
 
 // Assumes that both expressions have already been parsed
 // TODO(alex): be able to pass a random() function to compare()
-export const compare = function (expr1, expr2, options) {
-    var defaults = {
-        form: false, // Check that the two expressions have the same form
-        simplify: false, // Check that the second expression is simplified
+export const compare = function (
+    expr1: Expression,
+    expr2: Expression,
+    options: CompareOptions,
+): CompareResult {
+    const defaults: CompareOptions = {
+        form: false,
+        simplify: false,
     };
 
     /* Options that could be added in the future:
      * - Allow ratios: e.g. 3/1 and 3 should both be accepted for something
      *   like slope
      * - Allow student to choose their own variable names
      */
-
-    if (options !== undefined) {
-        // eslint-disable-next-line no-undef
-        options = _.extend(defaults, options);
-    } else {
-        options = defaults;
-    }
+    options = {...defaults, ...options};
 
     // TODO(CP-1614): Figure out how to make these messages translatable
 
     // Variable check
-    var vars = expr1.sameVars(expr2);
+    const vars = expr1.sameVars(expr2);
     if (!vars.equal) {
-        var message;
+        let message;
         if (vars.equalIgnoringCase) {
             message =
                 "Check your variables; one or more are using " +

packages/kas/src/parser-generator.js → packages/kas/src/parser-generator.ts

@@ -1,18 +1,14 @@
 #!/usr/bin/env node
 /* eslint-disable @typescript-eslint/no-var-requires */
-/* eslint-disable comma-dangle */
-/* eslint-disable comma-spacing */
 /* eslint-disable import/no-commonjs */
-/* eslint-disable max-len */
-/* eslint-disable no-var */
 /* eslint-disable prettier/prettier */
 
 const fs = require("fs");
 const path = require("path");
 
 const jison = require("jison");
 
-var grammar = {
+const grammar = {
     lex: {
         rules: [
             ["\\s+", "/* skip whitespace */"],
@@ -204,32 +200,32 @@ var grammar = {
     },
 };
 
-var prelude =
+const prelude =
     "// This is a @gene" + "rated file\n" + 'import _ from "underscore";\n\n';
-var parser = new jison.Generator(grammar).generate({moduleType: "js"});
+let parser = new jison.Generator(grammar).generate({moduleType: "js"});
 // NOTE(jeresig): We need to comment out these two labels as they appear to be
 // invalid ES5 (they also aren't referenced anywhere so this seems safe).
 parser = parser.replace(/(_token_stack:)/g, "//$1");
-var postlude = "\n\nexport {parser};\n";
+const postlude = "\n\nexport {parser};\n";
 
 fs.writeFileSync(
     path.resolve(__dirname, "__genfiles__", "parser.js"),
     prelude + parser + postlude,
 );
 
-var unitPrelude = "// this is a @gene" + "rated file\n\n";
-var unitEpilogue = "\n\nexport const unitParser = parser;\n";
+const unitPrelude = "// this is a @gene" + "rated file\n\n";
+const unitEpilogue = "\n\nexport const unitParser = parser;\n";
 
-var unitParserInfile = path.resolve(__dirname, "unitvalue.jison");
-var unitParserOutfile = path.resolve(
+const unitParserInfile = path.resolve(__dirname, "unitvalue.jison");
+const unitParserOutfile = path.resolve(
     __dirname,
     "__genfiles__",
     "unitparser.js",
 );
 
-var unitParserSource = fs.readFileSync(unitParserInfile);
-var unitParser = new jison.Generator(unitParserSource.toString());
-var generatedParser = unitParser.generate({moduleType: "js"});
+const unitParserSource = fs.readFileSync(unitParserInfile);
+const unitParser = new jison.Generator(unitParserSource.toString());
+let generatedParser = unitParser.generate({moduleType: "js"});
 // NOTE(jeresig): We need to comment out these two labels as they appear to be
 // invalid ES5 (they also aren't referenced anywhere so this seems safe).
 generatedParser = generatedParser.replace(/(_token_stack:)/g, "//$1");

packages/kas/src/types.d.ts

@@ -0,0 +1,25 @@
+export type CompareOptions = {
+    // Check that the two expressions have the same form
+    form: boolean;
+    // Check that the second expression is simplified
+    simplify: boolean;
+};
+
+export type CompareResult = {
+    equal: boolean;
+    wrongVariableCase?: boolean;
+    wrongVariableNames?: boolean;
+    message: string | null;
+};
+
+export type ExpressionVars = {
+    equal: boolean;
+    equalIgnoringCase: boolean;
+};
+
+export type Expression = {
+    compare: (expr: Expression) => boolean;
+    sameVars: (expr: Expression) => ExpressionVars;
+    sameForm: (expr: Expression) => unknown;
+    isSimplified: () => boolean;
+};