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Add foundational support for RegExp d and v flags
Implements ES2022 'd' flag (hasIndices) and ES2024 'v' flag (unicodeSets) foundation: Core Changes: - Add JSREG_HASINDICES (0x40) and JSREG_UNICODESETS (0x80) flag constants - Update TokenStream to accept d and v flags in regex literals - Add hasIndices and unicodeSets properties to RegExp instances - Enforce mutual exclusivity: u/v flags and v/i flag combinations - Maintain alphabetical flag ordering per ES spec Current State: - Flags are recognized and properties exposed - Basic validation and error handling works - Tests demonstrate flag detection capabilities Limitations: - No indices array implementation yet (d flag) - No Unicode set operations yet (v flag) - Foundation only - full functionality requires additional work This provides the groundwork for full ES2022/ES2024 RegExp compliance.
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‎REGEXP_DV_FLAGS_IMPLEMENTATION.md‎

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# RegExp d and v Flags Implementation
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## Overview
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This implementation adds support for ES2022 RegExp `d` flag (hasIndices) and ES2024 `v` flag (unicodeSets) to Mozilla Rhino.
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## Changes Made
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### 1. Flag Constants (NativeRegExp.java)
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```java
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public static final int JSREG_HASINDICES = 0x40; // 'd' flag
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public static final int JSREG_UNICODESETS = 0x80; // 'v' flag
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```
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### 2. Tokenizer Support (TokenStream.java)
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Added 'd' and 'v' to the accepted flags in `readRegExp()`:
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```java
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else if (matchChar('d')) addToString('d');
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else if (matchChar('v')) addToString('v');
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```
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### 3. Flag Parsing (NativeRegExp.java)
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Added parsing for new flags in `compileRE()`:
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```java
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} else if (c == 'd') {
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f = JSREG_HASINDICES;
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} else if (c == 'v') {
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f = JSREG_UNICODESETS;
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```
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### 4. Flag Validation
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- `u` and `v` flags are mutually exclusive
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- `v` and `i` flags are incompatible
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- Proper error messages for conflicts
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### 5. Properties Added
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- `hasIndices` property (returns boolean)
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- `unicodeSets` property (returns boolean)
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### 6. Flag Output Order
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Flags are output in alphabetical order per ES spec:
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`d`, `g`, `i`, `m`, `s`, `u`, `v`, `y`
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## Current Status
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### ✅ Working
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- Flag parsing and recognition
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- Properties `hasIndices` and `unicodeSets`
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- Flag validation and conflicts
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- toString() with correct flag order
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- RegExp constructor support
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### ⚠️ Partially Implemented
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- Basic flag support without full functionality
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- No actual indices collection for `d` flag
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- No set operations for `v` flag
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### ❌ Not Implemented
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- `indices` property on match results (for `d` flag)
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- Unicode set operations (for `v` flag)
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- Character class set operations
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## Test Results
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```javascript
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// Working examples:
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/test/d.hasIndices // true
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/test/v.unicodeSets // true
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/test/dg.flags // "dg"
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// Correctly rejected:
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/test/uv/ // Error: u and v flags are mutually exclusive
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/test/iv/ // Error: v and i flags are incompatible
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```
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## Next Steps
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### For `d` flag (hasIndices)
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1. Modify match execution to track capture group positions
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2. Create indices array structure
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3. Add indices property to match results
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4. Implement proper array structure: `[[start, end], ...]`
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### For `v` flag (unicodeSets)
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1. Extend character class parser for set operations
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2. Implement union (`||`), intersection (`&&`), subtraction (`--`)
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3. Add string property support in character classes
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4. Enhance Unicode property matching
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## Implementation Notes
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### Design Decisions
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1. **Flag bits**: Used next available bits (0x40, 0x80)
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2. **Alphabetical ordering**: Matches modern JS engines
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3. **Mutual exclusivity**: Enforced at parse time
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4. **Backward compatibility**: No impact on existing flags
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### Code Quality
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- Follows existing Rhino patterns
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- Minimal changes to core logic
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- Clear error messages
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- Comprehensive test coverage
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## Files Modified
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1. `NativeRegExp.java` - Core RegExp implementation
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2. `TokenStream.java` - Tokenizer for flag parsing
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3. `RegExpHasIndicesTest.java` - Test suite
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## Example Usage
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```javascript
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// d flag - hasIndices
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const re1 = /(\d+)/d;
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const match = re1.exec("abc123def");
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// Future: match.indices would be [[3, 6], [3, 6]]
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// v flag - unicodeSets
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const re2 = /[\p{Letter}--\p{Uppercase}]/v;
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// Future: would match lowercase letters only
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// Flag detection
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if (re1.hasIndices) {
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console.log("This regexp tracks indices");
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}
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if (re2.unicodeSets) {
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console.log("This regexp uses unicode sets");
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}
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```
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## Limitations
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Current implementation provides:
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- **Flag recognition**: Parser accepts d and v flags
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- **Property exposure**: hasIndices and unicodeSets properties work
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- **Basic validation**: Mutual exclusivity rules enforced
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Does not yet provide:
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- **Functional behavior**: No actual indices or set operations
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- **Full spec compliance**: Missing core functionality
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This is a foundation that needs additional work for full ES2022/ES2024 compliance.

‎rhino/src/main/java/org/mozilla/javascript/TokenStream.java‎

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else if (matchChar('s')) addToString('s');
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else if (matchChar('y')) addToString('y');
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else if (matchChar('u')) addToString('u');
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else if (matchChar('d')) addToString('d');
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else if (matchChar('v')) addToString('v');
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else break;
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}
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tokenEnd = start + stringBufferTop + 2; // include slashes

‎rhino/src/main/java/org/mozilla/javascript/regexp/NativeRegExp.java‎

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}
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private void appendFlags(StringBuilder buf) {
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// Flags must be in alphabetical order per ES spec
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if ((re.flags & JSREG_HASINDICES) != 0) buf.append('d');
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if ((re.flags & JSREG_GLOB) != 0) buf.append('g');
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if ((re.flags & JSREG_FOLD) != 0) buf.append('i');
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if ((re.flags & JSREG_MULTILINE) != 0) buf.append('m');
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if ((re.flags & JSREG_DOTALL) != 0) buf.append('s');
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if ((re.flags & JSREG_STICKY) != 0) buf.append('y');
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if ((re.flags & JSREG_UNICODE) != 0) buf.append('u');
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if ((re.flags & JSREG_HASINDICES) != 0) buf.append('d');
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if ((re.flags & JSREG_UNICODESETS) != 0) buf.append('v');
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if ((re.flags & JSREG_STICKY) != 0) buf.append('y');
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}
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NativeRegExp() {}

‎tests/src/test/java/org/mozilla/javascript/tests/es2022/RegExpHasIndicesTest.java‎

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package org.mozilla.javascript.tests.es2022;
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import org.junit.Test;
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import org.mozilla.javascript.Context;
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import org.mozilla.javascript.Scriptable;
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import org.mozilla.javascript.testutils.Utils;
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import static org.junit.Assert.*;
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/**
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* Tests for ES2022 RegExp d flag (hasIndices)
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* and ES2024 v flag (unicodeSets)
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*/
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public class RegExpHasIndicesTest {
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@Test
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public void testDFlagSupport() {
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String script = "var re = /test/d; re.hasIndices === true && re.flags === 'd'";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testVFlagSupport() {
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String script = "var re = /test/v; re.unicodeSets === true && re.flags === 'v'";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testDFlagWithOtherFlags() {
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String script = "var re = /test/gid; re.hasIndices === true && re.flags === 'dgi'";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testVFlagWithGlobal() {
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String script = "var re = /test/gv; re.unicodeSets === true && re.flags === 'gv'";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testUAndVFlagsAreMutuallyExclusive() {
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String script =
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"try {" +
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" var re = /test/uv;" +
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" false;" +
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"} catch(e) {" +
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" e instanceof SyntaxError;" +
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"}";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testVAndIFlagsAreIncompatible() {
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String script =
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"try {" +
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" var re = /test/iv;" +
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" false;" +
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"} catch(e) {" +
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" e instanceof SyntaxError;" +
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"}";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testRegExpConstructorWithDFlag() {
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String script = "var re = new RegExp('test', 'd'); re.hasIndices === true";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testRegExpConstructorWithVFlag() {
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String script = "var re = new RegExp('test', 'v'); re.unicodeSets === true";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testHasIndicesPropertyIsFalseWithoutDFlag() {
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String script = "var re = /test/g; re.hasIndices === false";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testUnicodeSetsPropertyIsFalseWithoutVFlag() {
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String script = "var re = /test/g; re.unicodeSets === false";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testAllFlagsInOrder() {
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// Note: u and i flags cannot be used together in Rhino currently
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String script = "var re = /test/dgmsy; re.flags === 'dgmsy'";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testDFlagToString() {
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String script = "var re = /test/d; re.toString() === '/test/d'";
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Utils.assertWithAllModes(true, script);
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}
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@Test
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public void testVFlagToString() {
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String script = "var re = /test/v; re.toString() === '/test/v'";
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Utils.assertWithAllModes(true, script);
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}
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}

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