Move toRegExp to index.js

demo/demo.js

@@ -22,15 +22,15 @@ function showOutput(el) {
   outputEl.classList.remove('error');
   let output = '';
   try {
-    // Don't actually run `toRegExp` in case the selected `target` includes features that don't
-    // work in the user's browser
+    // Use `compile` but display output as if `toRegExp` was called. This avoids erroring when the
+    // selected `target` includes features that don't work in the user's browser
     const re = compile(input, flags, {
       allowBestEffort: optionAllowBestEffortValue,
       maxRecursionDepth: optionMaxRecursionDepthValue === '' ? null : +optionMaxRecursionDepthValue,
       optimize: optionOptimizeValue,
       target: optionTargetValue,
     });
-    output = `/${regexize(re.pattern)}/${re.flags}`;
+    output = `/${getRegExpLiteralPattern(re.pattern)}/${re.flags}`;
   } catch (e) {
     outputEl.classList.add('error');
     output = `Error: ${e.message}`;
@@ -47,8 +47,8 @@ function escapeHtml(str) {
   return str.replace(/&/g, '&amp;').replace(/</g, '&lt;');
 }
 
-function regexize(str) {
-  return str === '' ? '(?:)' : str.replace(/\\?./gsu, m => m === '/' ? '\\/' : m);
+function getRegExpLiteralPattern(str) {
+  return str ? str.replace(/\\?./gsu, m => m === '/' ? '\\/' : m) : '(?:)';
 }
 
 function setFlagI(checked) {

demo/index.html

@@ -14,7 +14,7 @@ <h1>
         <img src="https://upload.wikimedia.org/wikipedia/commons/c/c2/GitHub_Invertocat_Logo.svg" width="25" height="25" alt="GitHub">
       </a>
     </h1>
-    <p>This is a basic REPL for testing the output of <a href="https://github.com/slevithan/oniguruma-to-es">Oniguruma-To-ES</a>, an <a href="https://github.com/kkos/oniguruma">Oniguruma</a> to JavaScript RegExp transpiler.</p>
+    <p>This is a basic REPL for testing the output of <a href="https://github.com/slevithan/oniguruma-to-es">Oniguruma-To-ES</a>, an Oniguruma to JavaScript RegExp transpiler. See <a href="https://github.com/kkos/oniguruma/blob/master/doc/RE">Oniguruma syntax</a>.</p>
 
     <h2>Try it</h2>
     <p><textarea id="input" spellcheck="false" oninput="showOutput(this); autoGrow(this)"></textarea></p>

src/compile.js

@@ -15,7 +15,7 @@ import {EsVersion, Target} from './utils.js';
 }} CompileOptions
 */
 /**
-Transpiles a regex pattern and flags from Oniguruma to native JS.
+Transpiles an Oniguruma regex pattern and flags to native JS.
 @param {string} pattern Oniguruma regex pattern.
 @param {import('./tokenize.js').OnigurumaFlags} [flags] Oniguruma flags. Flag m is equivalent to JS's flag s.
 @param {CompileOptions} [options]
@@ -27,7 +27,9 @@ Transpiles a regex pattern and flags from Oniguruma to native JS.
 function compile(pattern, flags, options) {
   const opts = getOptions(options);
   const tokenized = tokenize(pattern, flags);
-  const onigurumaAst = parse(tokenized, {optimize: opts.optimize});
+  const onigurumaAst = parse(tokenized, {
+    optimize: opts.optimize,
+  });
   const regexAst = transform(onigurumaAst, {
     allowBestEffort: opts.allowBestEffort,
     bestEffortTarget: opts.target,
@@ -66,20 +68,7 @@ function getOptions(options) {
   };
 }
 
-/**
-Transpiles a regex pattern and flags from Oniguruma to a native JS RegExp.
-@param {string} pattern Oniguruma regex pattern.
-@param {import('./tokenize.js').OnigurumaFlags} [flags] Oniguruma flags. Flag m is equivalent to JS's flag s.
-@param {CompileOptions} [options]
-@returns {RegExp}
-*/
-function toRegExp(pattern, flags, options) {
-  const result = compile(pattern, flags, options);
-  return new RegExp(result.pattern, result.flags);
-}
-
 export {
   compile,
   getOptions,
-  toRegExp,
 };

src/index.js

@@ -1,21 +1,20 @@
 import {transform} from './transform.js';
-import {compile, toRegExp} from './compile.js';
+import {compile} from './compile.js';
 import {parse} from './parse.js';
 import {tokenize} from './tokenize.js';
 
 // The transformation and error checking for Oniguruma's unique syntax and behavior differences
 // compared to native JS RegExp is layered into all steps of the compilation process:
-// 1. Tokenizer: Understands Oniguruma syntax (many large and small differences from JS).
+// 1. Tokenizer: Understands Oniguruma syntax, with many large and small differences from JS.
 // 2. Parser: Builds an Oniguruma AST from the tokens with understanding of Oniguruma differences.
 // 3. Transformer: Converts the Oniguruma AST to a `regex` AST that preserves all Oniguruma
-//    behavior. This is true even in cases of non-JS features that are supported by both `regex`
-//    and Oniguruma but with subtly different behavior (subroutines, flag x).
-// 4. Generator: Converts the `regex` AST to a `regex` pattern.
-// 5. `regex`: Components of the `regex` libray are used to transpile several remaining features
-//    that aren't native to JS RegExp (atomic groups, possessive quantifiers, recursion). `regex`
-//    uses a strict superset of JS RegExp syntax, so using it this way allows this library to
-//    benefit from not reinventing the wheel for features that `regex` already knows how to
-//    transpile to JS.
+//    behavior. This is true even in cases of non-native-JS features that are supported by both
+//    `regex` and Oniguruma but with subtly different behavior in each (subroutines, flag x).
+// 4. Generator: Converts the `regex` AST to a `regex` pattern, flags, and options.
+// 5. Compiler: Components of the `regex` libray are used to transpile several remaining features
+//    that aren't native to JS (atomic groups, possessive quantifiers, recursion). `regex` uses a
+//    strict superset of JS RegExp syntax, so using it allows this library to benefit from not
+//    reinventing the wheel for complex features that `regex` already knows how to transpile to JS.
 
 /**
 Generates an Oniguruma AST from an Oniguruma pattern and flags.
@@ -37,6 +36,18 @@ function toRegexAst(pattern, flags) {
   return transform(toOnigurumaAst(pattern, flags));
 }
 
+/**
+Transpiles an Oniguruma regex pattern and flags to a native JS RegExp.
+@param {string} pattern Oniguruma regex pattern.
+@param {import('./tokenize.js').OnigurumaFlags} [flags] Oniguruma flags. Flag m is equivalent to JS's flag s.
+@param {CompileOptions} [options]
+@returns {RegExp}
+*/
+function toRegExp(pattern, flags, options) {
+  const result = compile(pattern, flags, options);
+  return new RegExp(result.pattern, result.flags);
+}
+
 export {
   compile,
   toOnigurumaAst,