c495076adb
Suppose a parse state S has multiple actions for a terminal lookahead symbol A. Then during incremental parsing, while in state S, the parser should not reuse a non-terminal lookahead B where FIRST(B) contains A, because reusing B might prematurely discard one of the possible actions that a batch parser would have attempted in state S, upon seeing A as a lookahead.
40 lines
1.2 KiB
C++
40 lines
1.2 KiB
C++
#include "compiler/syntax_grammar.h"
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#include <vector>
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#include <string>
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#include <utility>
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#include "compiler/rules/symbol.h"
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#include "compiler/rules/built_in_symbols.h"
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namespace tree_sitter {
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using std::string;
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using std::to_string;
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using std::pair;
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using std::vector;
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using std::set;
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static const vector<Production> NO_PRODUCTIONS;
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SyntaxVariable::SyntaxVariable(const string &name, VariableType type,
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const vector<Production> &productions)
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: name(name), productions(productions), type(type) {}
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ProductionStep::ProductionStep(const rules::Symbol &symbol, int precedence,
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rules::Associativity associativity)
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: symbol(symbol), precedence(precedence), associativity(associativity) {}
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bool ProductionStep::operator==(const ProductionStep &other) const {
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return symbol == other.symbol && precedence == other.precedence &&
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associativity == other.associativity;
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}
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const vector<Production> &SyntaxGrammar::productions(
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const rules::Symbol &symbol) const {
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if (symbol.is_built_in() || symbol.is_token) {
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return NO_PRODUCTIONS;
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} else {
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return variables[symbol.index].productions;
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}
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}
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} // namespace tree_sitter
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