blob: f42aa1ae4dc2e0b6fa6e6901bba54b0104cc619a [file] [log] [blame]
* Copyright 2021 Google LLC.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#include <memory>
#include <unordered_map>
#include "include/core/SkStringView.h"
#include "include/private/SkSLProgramKind.h"
#include "include/private/SkTOptional.h"
#include "include/sksl/DSL.h"
#include "include/sksl/DSLSymbols.h"
#include "src/sksl/SkSLLexer.h"
#include "src/sksl/ir/SkSLProgram.h"
namespace SkSL {
class ErrorReporter;
struct Modifiers;
struct ParsedModule;
class SymbolTable;
* Consumes .sksl text and invokes DSL functions to instantiate the program.
class DSLParser {
enum class LayoutToken {
DSLParser(Compiler* compiler, const ProgramSettings& settings, ProgramKind kind,
String text);
std::unique_ptr<Program> program();
SkSL::LoadedModule moduleInheritingFrom(SkSL::ParsedModule baseModule);
skstd::string_view text(Token token);
PositionInfo position(Token token);
PositionInfo position(int line);
static void InitLayoutMap();
* Return the next token, including whitespace tokens, from the parse stream.
Token nextRawToken();
* Return the next non-whitespace token from the parse stream.
Token nextToken();
* Push a token back onto the parse stream, so that it is the next one read. Only a single level
* of pushback is supported (that is, it is an error to call pushback() twice in a row without
* an intervening nextToken()).
void pushback(Token t);
* Returns the next non-whitespace token without consuming it from the stream.
Token peek();
* Checks to see if the next token is of the specified type. If so, stores it in result (if
* result is non-null) and returns true. Otherwise, pushes it back and returns false.
bool checkNext(Token::Kind kind, Token* result = nullptr);
* Behaves like checkNext(TK_IDENTIFIER), but also verifies that identifier is not a builtin
* type. If the token was actually a builtin type, false is returned (the next token is not
* considered to be an identifier).
bool checkIdentifier(Token* result = nullptr);
* Reads the next non-whitespace token and generates an error if it is not the expected type.
* The 'expected' string is part of the error message, which reads:
* "expected <expected>, but found '<actual text>'"
* If 'result' is non-null, it is set to point to the token that was read.
* Returns true if the read token was as expected, false otherwise.
bool expect(Token::Kind kind, const char* expected, Token* result = nullptr);
bool expect(Token::Kind kind, String expected, Token* result = nullptr);
* Behaves like expect(TK_IDENTIFIER), but also verifies that identifier is not a type.
* If the token was actually a type, generates an error message of the form:
* "expected an identifier, but found type 'float2'"
bool expectIdentifier(Token* result);
void error(Token token, String msg);
void error(int line, String msg);
// these functions parse individual grammar rules from the current parse position; you probably
// don't need to call any of these outside of the parser. The function declarations in the .cpp
// file have comments describing the grammar rules.
void declarations();
SKSL_INT arraySize();
void directive();
bool declaration();
bool functionDeclarationEnd(const dsl::DSLModifiers& modifiers,
dsl::DSLType type,
const Token& name);
struct VarDeclarationsPrefix {
PositionInfo fPosition;
dsl::DSLModifiers fModifiers;
dsl::DSLType fType = dsl::DSLType(dsl::kVoid_Type);
Token fName;
bool varDeclarationsPrefix(VarDeclarationsPrefix* prefixData);
dsl::DSLStatement varDeclarationsOrExpressionStatement();
dsl::DSLStatement varDeclarations();
skstd::optional<dsl::DSLType> structDeclaration();
SkTArray<dsl::DSLGlobalVar> structVarDeclaration(const dsl::DSLModifiers& modifiers);
bool parseArrayDimensions(int line, dsl::DSLType* type);
bool parseInitializer(int line, dsl::DSLExpression* initializer);
void globalVarDeclarationEnd(PositionInfo position, const dsl::DSLModifiers& mods,
dsl::DSLType baseType, skstd::string_view name);
dsl::DSLStatement localVarDeclarationEnd(PositionInfo position, const dsl::DSLModifiers& mods,
dsl::DSLType baseType, skstd::string_view name);
skstd::optional<dsl::DSLWrapper<dsl::DSLParameter>> parameter(size_t paramIndex);
int layoutInt();
skstd::string_view layoutIdentifier();
dsl::DSLLayout layout();
dsl::DSLModifiers modifiers();
dsl::DSLStatement statement();
skstd::optional<dsl::DSLType> type(dsl::DSLModifiers* modifiers);
bool interfaceBlock(const dsl::DSLModifiers& mods);
dsl::DSLStatement ifStatement();
dsl::DSLStatement doStatement();
dsl::DSLStatement whileStatement();
dsl::DSLStatement forStatement();
skstd::optional<dsl::DSLCase> switchCase();
dsl::DSLStatement switchStatement();
dsl::DSLStatement returnStatement();
dsl::DSLStatement breakStatement();
dsl::DSLStatement continueStatement();
dsl::DSLStatement discardStatement();
skstd::optional<dsl::DSLBlock> block();
dsl::DSLStatement expressionStatement();
dsl::DSLExpression expression();
dsl::DSLExpression assignmentExpression();
dsl::DSLExpression ternaryExpression();
dsl::DSLExpression logicalOrExpression();
dsl::DSLExpression logicalXorExpression();
dsl::DSLExpression logicalAndExpression();
dsl::DSLExpression bitwiseOrExpression();
dsl::DSLExpression bitwiseXorExpression();
dsl::DSLExpression bitwiseAndExpression();
dsl::DSLExpression equalityExpression();
dsl::DSLExpression relationalExpression();
dsl::DSLExpression shiftExpression();
dsl::DSLExpression additiveExpression();
dsl::DSLExpression multiplicativeExpression();
dsl::DSLExpression unaryExpression();
dsl::DSLExpression postfixExpression();
dsl::DSLExpression swizzle(int line, dsl::DSLExpression base, skstd::string_view swizzleMask);
dsl::DSLExpression call(int line, dsl::DSLExpression base, ExpressionArray args);
dsl::DSLExpression suffix(dsl::DSLExpression base);
dsl::DSLExpression term();
bool intLiteral(SKSL_INT* dest);
bool floatLiteral(SKSL_FLOAT* dest);
bool boolLiteral(bool* dest);
bool identifier(skstd::string_view* dest);
class Checkpoint {
Checkpoint(DSLParser* p) : fParser(p) {
fPushbackCheckpoint = fParser->fPushback;
fLexerCheckpoint = fParser->fLexer.getCheckpoint();
fOldErrorReporter = &dsl::GetErrorReporter();
fOldEncounteredFatalError = fParser->fEncounteredFatalError;
~Checkpoint() {
"Checkpoint was not accepted or rewound before destruction");
void accept() {
// Parser errors should have been fatal, but we can encounter other errors like type
// mismatches despite accepting the parse. Forward those messages to the actual error
// handler now.
void rewind() {
fParser->fPushback = fPushbackCheckpoint;
fParser->fEncounteredFatalError = fOldEncounteredFatalError;
class ForwardingErrorReporter : public ErrorReporter {
void handleError(skstd::string_view msg, PositionInfo pos) override {
fErrors.push_back({String(msg), pos});
void forwardErrors() {
for (Error& error : fErrors) {
dsl::GetErrorReporter().error(error.fMsg.c_str(), error.fPos);
struct Error {
String fMsg;
PositionInfo fPos;
SkTArray<Error> fErrors;
void restoreErrorReporter() {
fOldErrorReporter = nullptr;
DSLParser* fParser;
Token fPushbackCheckpoint;
SkSL::Lexer::Checkpoint fLexerCheckpoint;
ForwardingErrorReporter fErrorReporter;
ErrorReporter* fOldErrorReporter;
bool fOldEncounteredFatalError;
static std::unordered_map<skstd::string_view, LayoutToken>* layoutTokens;
Compiler& fCompiler;
ProgramSettings fSettings;
ErrorReporter* fErrorReporter;
bool fEncounteredFatalError;
ProgramKind fKind;
std::unique_ptr<String> fText;
Lexer fLexer;
// current parse depth, used to enforce a recursion limit to try to keep us from overflowing the
// stack on pathological inputs
int fDepth = 0;
Token fPushback;
friend class AutoDSLDepth;
friend class HCodeGenerator;
} // namespace SkSL