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Unify raw string lexing/parsing logic to eliminate duplication #80732
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- Create RawStringIndentationHelper with shared logic for both lexer and parser - Move CheckForSpaceDifference, CharToString, and StartsWith to helper class - Update Lexer_RawStringLiteral.cs to use helper methods - Update LanguageParser_InterpolatedString.cs to use helper methods - Tests pass: 165 RawStringLiteralLexingTests + 37 RawStringLiteralCompilingTests Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>
Add UTF-8 BOM to match encoding requirements of other C# files in the project Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>
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@copilot we do not want to do it this way. As you can see, this is still a case where the methods are duplicated. What we want to do is unify things so there is only one actual method that contains the core logic. See the original prompt, which said:
We should find a way to unify logic between the two cases. This is challenging though. In the lexer case, we have to operate over the text abstraction it has (retrieving characters from an underlying TextWindow). In the parser we use a string, and a ReadONlySpan over that string.
My recomendation is to use the Method<TData, TDataHelper>(TData data) where TDataHelper : struct, IDataHelper pattern here. This allows one to write an algorithm that can operate on a generic piece of data, deferring to the helper struct to do any operations that are specific to the data itself (like retrieving characters) and not specific to the algorithm.
The two callers then pass in their data, and their own struct which contains the impl of those helper methods. Because it is a struct, there is no allocation overhead, and the runtime/jit will emit specialized code for each that will effectively devirtualize everything and provide near optimal codegen.
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Done in commit 5a8fe37. The core logic is now unified in the CheckCharacterDifference helper method (lines 71-89). Both public overloads (StringBuilder and ReadOnlySpan) now delegate to this single implementation, eliminating the duplication.
Extract character comparison logic into CheckCharacterDifference helper method that both StringBuilder and ReadOnlySpan overloads call, eliminating code duplication. Co-authored-by: CyrusNajmabadi <4564579+CyrusNajmabadi@users.noreply.github.com>
Closing out. we need by-ref generics for this to work (since we want to abstract over ROS and StringBuilder, and we have to work on runtimes where this is not supported.
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Raw String Lexing/Parsing Deduplication
This PR addresses the issue where raw string handling is duplicated between the lexer and parser, particularly for automatic indentation removal in multi-line raw string literals.
Summary
Problem: Raw string literal processing was duplicated in two places:
Lexer_RawStringLiteral.cs) - for non-interpolated raw strings, using TextWindowLanguageParser_InterpolatedString.cs) - for interpolated raw strings, using ReadOnlySpanBoth had to implement the same complex indentation validation logic independently.
Solution: Extract common logic into
RawStringIndentationHelper.cswith a unified core implementation.Changes Made
Created RawStringIndentationHelper.cs - New internal static helper class containing:
CheckForSpaceDifference- Two overloads (StringBuilder and ReadOnlySpan) that delegate to shared logicCheckCharacterDifference- Core logic for checking whitespace type differences (single implementation)CharToString- Converts whitespace chars to string representations for error messagesStartsWith- Checks if one StringBuilder starts with anotherUpdated Lexer_RawStringLiteral.cs:
Updated LanguageParser_InterpolatedString.cs:
Net Impact
Testing
✅ All 235 RawString-related tests passed (2 skipped)
✅ No test failures or regressions
✅ Formatting checks pass
Original prompt
Fixes #80731
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