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			41 lines
		
	
	
		
			2.1 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			41 lines
		
	
	
		
			2.1 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
| // Copyright 2023 Ron Buckton. All rights reserved.
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| // This code is governed by the BSD license found in the LICENSE file.
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| 
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| /*---
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| author: Ron Buckton
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| description: >
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|   Removing ignoreCase (`i`) modifier in group affects backreferences in group.
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| info: |
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|   Runtime Semantics: CompileAtom
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|   The syntax-directed operation CompileAtom takes arguments direction (forward or backward) and modifiers (a Modifiers Record) and returns a Matcher.
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| 
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|   Atom :: `(` `?` RegularExpressionFlags `-` RegularExpressionFlags `:` Disjunction `)`
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|     1. Let addModifiers be the source text matched by the first RegularExpressionFlags.
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|     2. Let removeModifiers be the source text matched by the second RegularExpressionFlags.
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|     3. Let newModifiers be UpdateModifiers(modifiers, CodePointsToString(addModifiers), CodePointsToString(removeModifiers)).
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|     4. Return CompileSubpattern of Disjunction with arguments direction and newModifiers.
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| 
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|   UpdateModifiers ( modifiers, add, remove )
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|   The abstract operation UpdateModifiers takes arguments modifiers (a Modifiers Record), add (a String), and remove (a String) and returns a Modifiers. It performs the following steps when called:
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| 
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|   1. Let dotAll be modifiers.[[DotAll]].
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|   2. Let ignoreCase be modifiers.[[IgnoreCase]].
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|   3. Let multiline be modifiers.[[Multiline]].
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|   4. If add contains "s", set dotAll to true.
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|   5. If add contains "i", set ignoreCase to true.
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|   6. If add contains "m", set multiline to true.
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|   7. If remove contains "s", set dotAll to false.
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|   8. If remove contains "i", set ignoreCase to false.
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|   9. If remove contains "m", set multiline to false.
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|   10. Return the Modifiers Record { [[DotAll]]: dotAll, [[IgnoreCase]]: ignoreCase, [[Multiline]]: multiline }.
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| 
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| esid: sec-compileatom
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| features: [regexp-modifiers]
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| ---*/
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| 
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| var re1 = /(a)(?-i:\1)/i;
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| assert(re1.test("AA"), "a matches first A, so \\1 should match second A");
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| assert(!re1.test("aA"), "a matches a, so \\1 should not match A (preserves case)");
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| assert(!re1.test("Aa"), "a matches A, so \\1 should not match a (preserves case)");
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| assert(re1.test("aa"), "a matches first a, so \\1 should match second a");
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