From cc49d87e3e0a56f2bc04db454a2180211e2c1eca Mon Sep 17 00:00:00 2001
From: Klaus <klahott@gmail.com>
Date: Wed, 11 Dec 2024 12:03:38 +1300
Subject: [PATCH] caching the parser for multiple calls to the parser

---
 src/slang-utils/create-parser.ts             | 15 ++++++--
 tests/unit/slang-utils/create-parser.test.js | 39 ++++++++++++++------
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/slang-utils/create-parser.ts b/src/slang-utils/create-parser.ts
index 99946b16..aa0eb2d5 100644
--- a/src/slang-utils/create-parser.ts
+++ b/src/slang-utils/create-parser.ts
@@ -34,18 +34,21 @@ const query = Query.parse(
   '[VersionPragma @versionRanges [VersionExpressionSets]]'
 );
 
+let parser: Parser;
+
 export function createParser(
   text: string,
   options: ParserOptions<AstNode>
 ): [Parser, ParseOutput] {
   const compiler = maxSatisfying(supportedVersions, options.compiler);
-  let parser: Parser;
   if (compiler) {
-    parser = Parser.create(compiler);
+    if (parser?.version !== compiler) {
+      parser = Parser.create(compiler);
+    }
     return [parser, parser.parse(NonterminalKind.SourceUnit, text)];
   }
 
-  parser = Parser.create(milestoneVersions[0]);
+  parser = parser ?? Parser.create(milestoneVersions[0]);
   let parseOutput;
   let inferredRanges: string[] = [];
 
@@ -53,7 +56,11 @@ export function createParser(
     parseOutput = parser.parse(NonterminalKind.SourceUnit, text);
     inferredRanges = tryToCollectPragmas(parseOutput, parser);
   } catch {
-    for (let i = 1; i <= milestoneVersions.length; i += 1) {
+    for (
+      let i = parser.version === milestoneVersions[0] ? 1 : 0;
+      i <= milestoneVersions.length;
+      i += 1
+    ) {
       try {
         const version = milestoneVersions[i];
         parser = Parser.create(version);
diff --git a/tests/unit/slang-utils/create-parser.test.js b/tests/unit/slang-utils/create-parser.test.js
index 6bacab62..4fabe59a 100644
--- a/tests/unit/slang-utils/create-parser.test.js
+++ b/tests/unit/slang-utils/create-parser.test.js
@@ -70,17 +70,6 @@ describe('inferLanguage', function () {
 0.8.2;`,
       version: '0.8.2'
     },
-    {
-      description: 'should use the latest version if the source has no pragmas',
-      source: `contract Foo {}`,
-      version: latestSupportedVersion
-    },
-    {
-      description:
-        'should use the latest valid version if the source has no pragmas and the syntax is old',
-      source: `contract Foo {byte bar;}`,
-      version: '0.7.6'
-    },
     {
       description:
         'should use the latest version if the range is outside the supported versions',
@@ -96,6 +85,34 @@ describe('inferLanguage', function () {
     });
   }
 
+  test('should use the cached or the latest successful version if the source has no pragmas', function () {
+    createParser(`pragma solidity 0.8.28;`, options);
+    let [parser] = createParser(`contract Foo {}`, options);
+    expect(parser.version).toEqual('0.8.28');
+
+    createParser(`pragma solidity 0.8.2;`, options);
+    [parser] = createParser(`contract Foo {}`, options);
+    expect(parser.version).toEqual('0.8.2');
+
+    [parser] = createParser(`contract Foo {byte bar;}`, options);
+    expect(parser.version).toEqual('0.7.6');
+  });
+
+  test('should use compiler option if given', function () {
+    let [parser] = createParser(`pragma solidity ^0.8.0;`, {
+      compiler: '0.8.20'
+    });
+    expect(parser.version).toEqual('0.8.20');
+
+    [parser] = createParser(`pragma solidity ^0.8.0;`, {
+      compiler: '0.8.2'
+    });
+    expect(parser.version).toEqual('0.8.2');
+
+    [parser] = createParser(`pragma solidity ^0.8.0;`, {});
+    expect(parser.version).toEqual(latestSupportedVersion);
+  });
+
   test('should throw when a pragma is broken by new lines, whitespace and comments', function () {
     expect(() =>
       createParser(