Enable switch statements by AprupKale · Pull Request #67 · source-academy/java-slang

AprupKale · 2025-02-18T05:21:31Z

Enable switch statements to support code as follows:

public class Main {
    public static void main(String[] args) {
        int x = 2;
        
        switch (x) {
            case 1:
                System.out.println("One");
                break;
            case 2:
                System.out.println("Two");
                break;
            case 3:
                System.out.println("Three");
                break;
            default:
                System.out.println("Default");
        }
    }
}

…int, byte, short, char)

github-actions · 2025-02-18T05:23:32Z

Coverage report

St.^❔	Category	Percentage	Covered / Total
🟡	Statements	74.37% (+0.42% 🔼)	7510/10098
🟡	Branches	60.74% (+0.35% 🔼)	2519/4147
🟡	Functions	70.24% (+0.79% 🔼)	1336/1902
🟡	Lines	75.3% (+0.36% 🔼)	7080/9403

Show new covered files 🐣

St.^❔	File	Statements	Branches	Functions	Lines
🟢	`...` / assignmentExpression.test.ts	100%	100%	100%	100%
🟢	`...` / castExpression.test.ts	100%	100%	100%	100%
🟢	`...` / switch.test.ts	100%	100%	100%	100%

Show files with reduced coverage 🔻

St.^❔	File	Statements	Branches	Functions	Lines
🟡	`...` / index.ts	70.8% (-3.57% 🔻)	48% (-5.01% 🔻)	91.67% (-3.99% 🔻)	79.3% (-4.94% 🔻)
🟢	`...` / code-generator.ts	92.24% (-2.17% 🔻)	77.23% (-7.42% 🔻)	95.89% (+2.71% 🔼)	92.33% (-2.42% 🔻)

Test suite run success

1159 tests passing in 64 suites.

Report generated by 🧪jest coverage report action from 91691ad

martin-henz · 2026-05-28T03:47:43Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces support for parsing, type-checking, and compiling Java-style CastExpression and SwitchStatement constructs. Key changes include updating the PEG.js grammar, extending AST types, implementing AST extractors, handling implicit and explicit type conversions, and generating JVM bytecode for switch statements (including TABLESWITCH, LOOKUPSWITCH, and string switches). Comprehensive test suites have also been added. The review feedback highlights several critical issues: a bug in the implicit type conversion logic where the in operator is incorrectly used instead of Array.prototype.includes(), unsafe deep property access in the expression extractor that could lead to crashes, and a parsing issue where parseInt is incorrectly applied to character literals in switch cases. Additionally, it is recommended to clean up leftover console.log statements and commented-out code blocks.

gemini-code-assist · 2026-05-28T03:48:34Z

+    if (!(fromType in ['J', 'D']) && toType in ['J', 'D']) {
+      return 1;
+    } else if (!(toType in ['J', 'D']) && fromType in ['J', 'D']) {
+      return -1;
+    } else {


The in operator in JavaScript/TypeScript checks for the presence of a property/index in an object or array, not the presence of a value in an array. For example, 'J' in ['J', 'D'] evaluates to false because the array only has indices '0' and '1'. This will cause the implicit type conversion logic to fail or behave incorrectly.

Use Array.prototype.includes() instead to check if the array contains the type.

Suggested change

if (!(fromType in ['J', 'D']) && toType in ['J', 'D']) {

return 1;

} else if (!(toType in ['J', 'D']) && fromType in ['J', 'D']) {

return -1;

} else {

if (!['J', 'D'].includes(fromType) && ['J', 'D'].includes(toType)) {

return 1;

} else if (!['J', 'D'].includes(toType) && ['J', 'D'].includes(fromType)) {

return -1;

} else {

gemini-code-assist · 2026-05-28T03:48:34Z

+      cases.forEach((caseGroup, index) => {
+        caseGroup.labels.forEach((label) => {
+          if (label.kind === "CaseLabel") {
+            const value = parseInt((label.expression as Literal).literalType.value);


Using parseInt directly on the literal value will fail for character literals (e.g., 'A'), returning NaN. This will break switch statements over char types.

You should check if the literal is a CharacterLiteral and use charCodeAt(0) to get its integer value, or handle it appropriately based on the literal kind.

Suggested change

const value = parseInt((label.expression as Literal).literalType.value);

const literal = label.expression as Literal;

const value = literal.literalType.kind === "CharacterLiteral"

? literal.literalType.value.charCodeAt(0)

: parseInt(literal.literalType.value);

gemini-code-assist · 2026-05-28T03:48:34Z

+    if (ctx.primary[0].children.primaryPrefix[0].children.castExpression) {
+      return this.visit(ctx.primary[0].children.primaryPrefix[0].children.castExpression);
+    }


This expression performs deep nested property access (ctx.primary[0].children.primaryPrefix[0].children.castExpression) without checking if the intermediate arrays or objects exist. If ctx.primary is empty, or primaryPrefix is empty/undefined, this will throw a TypeError and crash the parser.

Use optional chaining to safely check for the existence of these properties.

Suggested change

if (ctx.primary[0].children.primaryPrefix[0].children.castExpression) {

return this.visit(ctx.primary[0].children.primaryPrefix[0].children.castExpression);

}

if (ctx.primary?.[0]?.children?.primaryPrefix?.[0]?.children?.castExpression) {

return this.visit(ctx.primary[0].children.primaryPrefix[0].children.castExpression);

}

gemini-code-assist · 2026-05-28T03:48:34Z

+  switchBlockStatementGroup(ctx: SwitchBlockStatementGroupCtx): SwitchCase {
+    const blockStatementExtractor = new BlockStatementExtractor();
+
+    console.log(ctx.switchLabel)


Remove leftover console.log used for debugging to keep the codebase clean.

gemini-code-assist · 2026-05-28T03:48:34Z

+  // switchLabel(ctx: SwitchLabelCtx): CaseLabel | DefaultLabel {
+  //   // Check if the context contains a "case" label
+  //   if (ctx.caseOrDefaultLabel?.[0]?.children?.Case) {
+  //     const expressionExtractor = new ExpressionExtractor();
+  //     // @ts-ignore
+  //     const expressionCtx = ctx.caseOrDefaultLabel[0].children.caseLabelElement[0]
+  //       .children.caseConstant[0].children.ternaryExpression[0].children;
+  //
+  //     // Ensure the expression context is valid before proceeding
+  //     if (!expressionCtx) {
+  //       throw new Error("Invalid Case expression in switch label");
+  //     }
+  //
+  //     const expression = expressionExtractor.ternaryExpression(expressionCtx);
+  //
+  //     return {
+  //       kind: "CaseLabel",
+  //       expression: expression,
+  //     };
+  //   }
+  //
+  //   // Check if the context contains a "default" label
+  //   if (ctx.caseOrDefaultLabel?.[0]?.children?.Default) {
+  //     return { kind: "DefaultLabel" };
+  //   }
+  //
+  //   // Throw an error if the context does not match expected patterns
+  //   throw new Error("Invalid switch label: Neither 'case' nor 'default' found");
+  // }


Avoid leaving large blocks of commented-out code in the codebase. If this implementation of switchLabel is no longer needed, it should be removed entirely.

gemini-code-assist · 2026-05-28T03:48:34Z

+// function generateBooleanConversion(type: string, cg: CodeGenerator): number {
+//   let stackChange = 0; // Tracks changes to the stack size
+//
+//   switch (type) {
+//     case 'I': // int
+//     case 'B': // byte
+//     case 'S': // short
+//     case 'C': // char
+//       // For integer-like types, compare with zero
+//       cg.code.push(OPCODE.ICONST_0); // Push 0
+//       stackChange += 1; // `ICONST_0` pushes a value onto the stack
+//       cg.code.push(OPCODE.IF_ICMPNE); // Compare and branch
+//       stackChange -= 2; // `IF_ICMPNE` consumes two values from the stack
+//       break;
+//
+//     case 'J': // long
+//       // For long, compare with zero
+//       cg.code.push(OPCODE.LCONST_0); // Push 0L
+//       stackChange += 2; // `LCONST_0` pushes two values onto the stack (long takes 2 slots)
+//       cg.code.push(OPCODE.LCMP); // Compare top two longs
+//       stackChange -= 4; // `LCMP` consumes four values (two long operands) and pushes one result
+//       cg.code.push(OPCODE.IFNE); // If not equal, branch
+//       stackChange -= 1; // `IFNE` consumes one value (the comparison result)
+//       break;
+//
+//     case 'F': // float
+//       // For float, compare with zero
+//       cg.code.push(OPCODE.FCONST_0); // Push 0.0f
+//       stackChange += 1; // `FCONST_0` pushes a value onto the stack
+//       cg.code.push(OPCODE.FCMPL); // Compare top two floats
+//       stackChange -= 2; // `FCMPL` consumes two values (float operands) and pushes one result
+//       cg.code.push(OPCODE.IFNE); // If not equal, branch
+//       stackChange -= 1; // `IFNE` consumes one value (the comparison result)
+//       break;
+//
+//     case 'D': // double
+//       // For double, compare with zero
+//       cg.code.push(OPCODE.DCONST_0); // Push 0.0d
+//       stackChange += 2; // `DCONST_0` pushes two values onto the stack (double takes 2 slots)
+//       cg.code.push(OPCODE.DCMPL); // Compare top two doubles
+//       stackChange -= 4; // `DCMPL` consumes four values (two double operands) and pushes one result
+//       cg.code.push(OPCODE.IFNE); // If not equal, branch
+//       stackChange -= 1; // `IFNE` consumes one value (the comparison result)
+//       break;
+//
+//     case 'Z': // boolean
+//       // Already a boolean, no conversion needed
+//       break;
+//
+//     default:
+//       throw new Error(`Cannot convert type ${type} to boolean.`);
+//   }
+//
+//   return stackChange; // Return the net change in stack size
+// }


Avoid leaving large blocks of commented-out code in the codebase. If generateBooleanConversion is no longer needed, it should be removed.

AprupKale added 15 commits January 14, 2025 14:53

Add opcodes for type conversions to code-generator.ts

70eedf6

Add implicit type conversions in MethodInvocation to code-generator.ts

64e245d

Add implicit type conversions in MethodInvocation to code-generator.ts

a33c9af

Handle stack size during primitive type conversions in code-generator.ts

1848b4d

Handle type conversions in binary expressions in code-generator.ts

f88069e

Fix bugs with float conversions

db87720

Allow primitive types to be safely converted to String

6e0a2d7

Allow primitive types other than boolean in ternary conditional

7e58159

Fix bugs in type checker

6bbafe7

Enable unary expressions for non-integer types

57eeb8b

Fix bug in type conversion for binary expressions

2a2cc0b

Add type cast support to the compiler

0799bf7

Add type cast support to the type checker

fe76603

Add switch statement support to the AST extractor and the compiler

345a8c8

Add switch statement support to the compiler for integer like types (…

2038d8b

…int, byte, short, char)

AprupKale self-assigned this Feb 18, 2025

AprupKale added the enhancement New feature or request label Feb 18, 2025

Add switch statement support to the compiler for String type

91691ad

AprupKale marked this pull request as ready for review February 18, 2025 08:39

gemini-code-assist Bot reviewed May 28, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Enable switch statements#67

Enable switch statements#67
AprupKale wants to merge 16 commits into
mainfrom
switch-statements

AprupKale commented Feb 18, 2025 •

edited

Loading

Uh oh!

github-actions Bot commented Feb 18, 2025 •

edited

Loading

Uh oh!

martin-henz commented May 28, 2026

Uh oh!

gemini-code-assist Bot left a comment

Uh oh!

gemini-code-assist Bot May 28, 2026

Uh oh!

gemini-code-assist Bot May 28, 2026

Uh oh!

gemini-code-assist Bot May 28, 2026

Uh oh!

gemini-code-assist Bot May 28, 2026

Uh oh!

gemini-code-assist Bot May 28, 2026

Uh oh!

gemini-code-assist Bot May 28, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

-            const value = parseInt((label.expression as Literal).literalType.value);
+            const literal = label.expression as Literal;
+            const value = literal.literalType.kind === "CharacterLiteral"
+              ? literal.literalType.value.charCodeAt(0)
+              : parseInt(literal.literalType.value);

Conversation

AprupKale commented Feb 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

github-actions Bot commented Feb 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Coverage report

Test suite run success

Uh oh!

martin-henz commented May 28, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist Bot May 28, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot May 28, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot May 28, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot May 28, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot May 28, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot May 28, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

AprupKale commented Feb 18, 2025 •

edited

Loading

github-actions Bot commented Feb 18, 2025 •

edited

Loading