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			53 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			53 lines
		
	
	
		
			2.7 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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author: Ron Buckton
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description: >
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  Adding 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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  Atom :: `(` `?` RegularExpressionFlags `:` Disjunction `)`
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    1. Let addModifiers be the source text matched by RegularExpressionFlags.
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    2. Let removeModifiers be the empty String.
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    3. Let newModifiers be UpdateModifiers(modifiers, CodePointsToString(addModifiers), removeModifiers).
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    4. Return CompileSubpattern of Disjunction with arguments direction and newModifiers.
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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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  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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  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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esid: sec-compileatom
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features: [regexp-modifiers]
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---*/
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var re1 = /(a)(?i:\1)/;
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assert(!re1.test("AA"), "a should not match first A");
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assert(!re1.test("Aa"), "a should not match A");
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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 match A (ignores case)");
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var re2 = /(a)(?i-:\1)/;
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assert(!re2.test("AA"), "a should not match first A");
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assert(!re2.test("Aa"), "a should not match A");
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assert(re2.test("aa"), "a matches first a, so \\1 should match second a");
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assert(re2.test("aA"), "a matches a, so \\1 should match A (ignores case)");
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