SkSL::Mangler Class Reference

#include <SkSLMangler.h>

Public Member Functions
std::string	uniqueName (std::string_view baseName, SymbolTable *symbolTable)
void	reset ()

Detailed Description

Definition at line 18 of file SkSLMangler.h.

Member Function Documentation

reset()

void SkSL::Mangler::reset ( )

inline

Definition at line 25 of file SkSLMangler.h.

                 {
        fCounter = 0;
    }

uniqueName()

std::string SkSL::Mangler::uniqueName	(	std::string_view	baseName,
		SymbolTable *	symbolTable
	)

Mangles baseName to create a name that is unique within symbolTable.

Definition at line 21 of file SkSLMangler.cpp.

                                                                               {
    SkASSERT(symbolTable);
 
    // Private names might begin with a $. Strip that off.
    if (skstd::starts_with(baseName, '$')) {
        baseName.remove_prefix(1);
    }
 
    // The inliner runs more than once, so the base name might already have been mangled and have a
    // prefix like "_123_x". Let's strip that prefix off to make the generated code easier to read.
    if (skstd::starts_with(baseName, '_')) {
        // Determine if we have a string of digits.
        int offset = 1;
        while (isdigit(baseName[offset])) {
            ++offset;
        }
        // If we found digits, another underscore, and anything else, that's the mangler prefix.
        // Strip it off.
        if (offset > 1 && baseName[offset] == '_' && baseName[offset + 1] != '\0') {
            baseName.remove_prefix(offset + 1);
        } else {
            // This name doesn't contain a mangler prefix, but it does start with an underscore.
            // OpenGL disallows two consecutive underscores anywhere in the string, and we'll be
            // adding one as part of the mangler prefix, so strip the leading underscore.
            baseName.remove_prefix(1);
        }
    }
 
    // Append a unique numeric prefix to avoid name overlap. Check the symbol table to make sure
    // we're not reusing an existing name. (Note that within a single compilation pass, this check
    // isn't fully comprehensive, as code isn't always generated in top-to-bottom order.)
 
    // This code is a performance hotspot. Assemble the string manually to save a few cycles.
    char uniqueName[256];
    uniqueName[0] = '_';
    char* uniqueNameEnd = uniqueName + std::size(uniqueName);
    for (;;) {
        // _123
        char* endPtr = SkStrAppendS32(uniqueName + 1, fCounter++);
 
        // _123_
        *endPtr++ = '_';
 
        // _123_baseNameTruncatedToFit (no null terminator, because string_view doesn't require one)
        int baseNameCopyLength = std::min<int>(baseName.size(), uniqueNameEnd - endPtr);
        memcpy(endPtr, baseName.data(), baseNameCopyLength);
        endPtr += baseNameCopyLength;
 
        std::string_view uniqueNameView(uniqueName, endPtr - uniqueName);
        if (symbolTable->find(uniqueNameView) == nullptr) {
            return std::string(uniqueNameView);
        }
    }
}

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The documentation for this class was generated from the following files:

• third_party/skia/src/sksl/SkSLMangler.h
• third_party/skia/src/sksl/SkSLMangler.cpp