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Fix parsing of (λx.x)λx.x

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This commit is contained in:
Arne Keller 2021-02-03 16:09:58 +01:00
parent b87e444f0b
commit 62d7c9f5e1
3 changed files with 30 additions and 5 deletions
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11
src/main/java/edu/kit/typicalc/model/parser/LambdaParser.java
View File

@ -107,6 +107,8 @@ public class LambdaParser {
return new Result<>(let);
}
return new Result<>(let.unwrap());
case VARIABLE:
return new Result<>(parseApplication());
case EOF:
return new Result<>(null, ParseError.TOO_FEW_TOKENS);
default:
@ -140,8 +142,13 @@ public class LambdaParser {
if (left.isError()) {
return left;
}
while (ATOM_START_TOKENS.contains(token.getType())) {
Result<LambdaTerm, ParseError> atom = parseAtom();
while (ATOM_START_TOKENS.contains(token.getType()) || token.getType() == TokenType.LAMBDA) {
Result<LambdaTerm, ParseError> atom;
if (token.getType() == TokenType.LAMBDA) {
atom = new Result<>(parseAbstraction());
} else {
atom = parseAtom();
}
if (atom.isError()) {
return atom;
}

4
src/main/java/edu/kit/typicalc/util/Result.java
View File

@ -71,7 +71,7 @@ public class Result<T, E> {
*/
public T unwrap() throws IllegalStateException {
if (value == null) {
throw new IllegalStateException("tried to unwrap an error");
throw new IllegalStateException("tried to unwrap a result, but error = " + error);
}
return value;
}
@ -85,7 +85,7 @@ public class Result<T, E> {
*/
public E unwrapError() {
if (error == null) {
throw new IllegalStateException("tried to unwrap a value");
throw new IllegalStateException("tried to unwrap the error, but value = " + value);
}
return error;
}

20
src/test/java/edu/kit/typicalc/model/parser/LambdaParserTest.java
View File

@ -15,6 +15,8 @@ import nl.jqno.equalsverifier.EqualsVerifier;
import org.junit.jupiter.api.Test;
class LambdaParserTest {
private static final VarTerm X = new VarTerm("x");
@Test
void varTerm() {
LambdaParser parser = new LambdaParser("x");
@ -63,6 +65,11 @@ class LambdaParserTest {
@Test
void complicatedTerm() {
LambdaParser parser = new LambdaParser("(λx.λy.x y 5)(λz.z)(true)");
Result<LambdaTerm, ParseError> term = parser.parse();
if (term.isError()) {
System.err.println(term.unwrapError());
System.err.println(term.unwrapError().getCause());
}
assertEquals(
new AppTerm(
new AppTerm(
@ -86,7 +93,7 @@ class LambdaParserTest {
),
new BooleanTerm(true)
),
parser.parse().unwrap()
term.unwrap()
);
}
@Test
@ -139,6 +146,17 @@ class LambdaParserTest {
assertEquals(new Token(TokenType.RIGHT_PARENTHESIS, ")", 13), error.getCause());
}
@Test
void bugFoundByThomas() {
LambdaParser parser = new LambdaParser("(λx. x) λx. x");
Result<LambdaTerm, ParseError> term = parser.parse();
if (term.isError()) {
System.err.println(term.unwrapError());
System.err.println(term.unwrapError().getCause());
}
assertEquals(new AppTerm(new AbsTerm(X, X), new AbsTerm(X, X)), term.unwrap());
}
@Test
void equality() {
EqualsVerifier.forClass(Token.class).usingGetClass().verify();