48baf056b4
This way, we can keep of the order in which the rules were given, for resolving reduce/reduce conflicts.
51 lines
1.7 KiB
C++
51 lines
1.7 KiB
C++
#include "compiler_spec_helper.h"
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#include "compiler/prepared_grammar.h"
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#include "compiler/build_tables/follow_sets.h"
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using std::set;
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using namespace build_tables;
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using namespace rules;
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START_TEST
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describe("computing FOLLOW sets", []() {
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const PreparedGrammar grammar({
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{ "A", sym("a") },
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{ "B", sym("b") },
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}, {});
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it("includes all of the starting non-terminals for the item, and their following terminals", [&]() {
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ParseItem item(Symbol("C"), choice({
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seq({ sym("A"), choice({ sym("x"), sym("y") }) }),
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seq({ sym("B"), sym("z") }),
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}), {}, Symbol("w"));
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AssertThat(follow_sets(item, grammar), Equals(map<Symbol, set<Symbol>>({
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{ Symbol("A"), set<Symbol>({ Symbol("x"), Symbol("y") }) },
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{ Symbol("B"), set<Symbol>({ Symbol("z") }) },
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})));
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});
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it("does not include terminals at the beginning of the item", [&]() {
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ParseItem item(Symbol("C"), choice({
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seq({ sym("A"), choice({ sym("x"), sym("y") }) }),
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seq({ sym("x"), sym("y") }),
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}), {}, Symbol("w"));
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AssertThat(follow_sets(item, grammar), Equals(map<Symbol, set<Symbol>>({
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{ Symbol("A"), set<Symbol>({ Symbol("x"), Symbol("y") }) },
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})));
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});
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it("includes the item's lookahead terminal if the rule after the non-terminal might be blank", [&]() {
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ParseItem item(Symbol("C"), choice({
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seq({ sym("A"), choice({ sym("x"), blank() }) }),
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}), {}, Symbol("w"));
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AssertThat(follow_sets(item, grammar), Equals(map<Symbol, set<Symbol>>({
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{ Symbol("A"), set<Symbol>({ Symbol("x"), Symbol("w") }) },
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})));
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});
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});
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END_TEST
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