1cc7e32e2d
The parser is no longer hard-coded to skip whitespace. Tokens such as newlines, whose characters overlap with the separator characters, can now be correctly recognized.
97 lines
2.7 KiB
C++
97 lines
2.7 KiB
C++
#include "compiler_spec_helper.h"
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#include "compiler/prepared_grammar.h"
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#include "compiler/build_tables/first_set.h"
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#include "compiler/rules/metadata.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 FIRST sets", []() {
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const PreparedGrammar null_grammar({}, {});
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describe("for a sequence AB", [&]() {
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it("ignores B when A cannot be blank", [&]() {
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auto rule = seq({ sym("x"), sym("y") });
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AssertThat(first_set(rule, null_grammar), Equals(set<Symbol>({
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Symbol("x"),
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})));
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});
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it("includes FIRST(B) when A can be blank", [&]() {
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auto rule = seq({
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choice({
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sym("x"),
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blank() }),
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sym("y") });
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AssertThat(first_set(rule, null_grammar), Equals(set<Symbol>({
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Symbol("x"),
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Symbol("y")
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})));
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});
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it("includes FIRST(A's right hand side) when A is a non-terminal", [&]() {
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auto rule = choice({
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seq({
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sym("A"),
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sym("x"),
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sym("A") }),
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sym("A") });
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Grammar grammar({
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{ "A", choice({
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seq({
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sym("y"),
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sym("z"),
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sym("y") }),
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sym("y") }) }
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});
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AssertThat(first_set(rule, grammar), Equals(set<Symbol>({
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Symbol("y")
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})));
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});
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it("includes FIRST(B) when A is a non-terminal and its expansion can be blank", [&]() {
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Grammar grammar({{ "A", choice({ sym("x"), blank() }) }});
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auto rule = seq({
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sym("A"),
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sym("y") });
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AssertThat(first_set(rule, grammar), Equals(set<Symbol>({
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Symbol("x"),
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Symbol("y")
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})));
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});
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});
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describe("when there are left-recursive rules", [&]() {
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it("terminates", [&]() {
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Grammar grammar({
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{ "expression", choice({
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seq({ sym("expression"), sym("x") }),
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sym("y"),
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}) },
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});
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AssertThat(first_set(sym("expression"), grammar), Equals(set<Symbol>({
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Symbol("y")
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})));
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});
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});
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it("ignores metadata rules", [&]() {
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auto rule = make_shared<Metadata>(sym("x"), MetadataValue(1));
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AssertThat(first_set(rule, null_grammar), Equals(set<Symbol>({
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Symbol("x"),
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})));
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});
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});
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END_TEST
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