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package org.shedlang.compiler.tokeniser;
import org.junit.jupiter.api.Test;
import org.zwobble.sourcetext.SourceText;
import java.util.List;
import static org.junit.jupiter.api.Assertions.fail;
import static org.zwobble.precisely.AssertThat.assertThat;
import static org.zwobble.precisely.Matchers.equalTo;
public class TokenIteratorTests {
enum TokenType {
IDENTIFIER,
SYMBOL,
END
}
@Test
public void skipSucceedsWhenNextTokenHasMatchingTokenType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
tokens.skip(TokenType.IDENTIFIER);
tokens.skip(TokenType.SYMBOL);
tokens.skip(TokenType.END);
tokens.skip(TokenType.END);
}
@Test
public void skipFailsWhenNextTokenDoesNotHaveMatchingTokenType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
try {
tokens.skip(TokenType.SYMBOL);
fail("expected exception");
} catch (UnexpectedTokenException exception) {
assertThat(exception.getMessage(), equalTo("Expected: SYMBOL\nBut got: IDENTIFIER \"x\""));
}
}
@Test
public void trySkipAdvancesIteratorAndReturnsTrueWhenNextTokenHasMatchingTokenType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
assertThat(tokens.trySkip(TokenType.SYMBOL), equalTo(true));
assertThat(tokens.trySkip(TokenType.IDENTIFIER), equalTo(true));
assertThat(tokens.trySkip(TokenType.SYMBOL), equalTo(true));
assertThat(tokens.trySkip(TokenType.END), equalTo(true));
assertThat(tokens.trySkip(TokenType.END), equalTo(true));
}
@Test
public void trySkipDoesNotAdvanceIteratorAndReturnsFalseWhenNextTokenDoesNotHaveMatchingTokenType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.trySkip(TokenType.SYMBOL), equalTo(false));
assertThat(tokens.trySkip(TokenType.IDENTIFIER), equalTo(true));
}
@Test
public void nextValueReturnsValueWhenCurrentTokenHasMatchingTokenType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
assertThat(tokens.nextValue(TokenType.SYMBOL), equalTo("!"));
assertThat(tokens.nextValue(TokenType.IDENTIFIER), equalTo("x"));
}
@Test
public void nextValueFailsWhenCurrentTokenDoesNotHaveMatchingTokenType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
try {
tokens.nextValue(TokenType.SYMBOL);
fail("expected exception");
} catch (UnexpectedTokenException exception) {
assertThat(exception.getMessage(), equalTo("Expected: SYMBOL\nBut got: IDENTIFIER \"x\""));
}
}
@Test
public void isNextWithOneArgReturnsTrueIfNextTokenIsOfMatchingType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.isNext(TokenType.IDENTIFIER), equalTo(true));
}
@Test
public void isNextWithOneArgReturnsFalseIfNextTokenIsNotOfMatchingType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.isNext(TokenType.SYMBOL), equalTo(false));
}
@Test
public void isNextWithTwoArgReturnsTrueIfBothNextTokensMatchRespectiveTypes() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.isNext(TokenType.IDENTIFIER, TokenType.SYMBOL), equalTo(true));
}
@Test
public void isNextWithTwoArgReturnsFalseIfFirstTokenDoesNotMatchRespectiveType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.isNext(TokenType.SYMBOL, TokenType.SYMBOL), equalTo(false));
}
@Test
public void isNextWithTwoArgReturnsFalseIfSecondTokenDoesNotMatchRespectiveType() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.isNext(TokenType.IDENTIFIER, TokenType.IDENTIFIER), equalTo(false));
}
@Test
public void peekReturnsNextTokenWithoutAdvancing() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
assertThat(tokens.peek(), equalTo(token(sourceText, 0, 1, TokenType.SYMBOL)));
assertThat(tokens.peek(), equalTo(token(sourceText, 0, 1, TokenType.SYMBOL)));
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.peek(), equalTo(token(sourceText, 1, 2, TokenType.IDENTIFIER)));
}
@Test
public void canPeekMultipleTokensAhead() {
var sourceText = SourceText.fromString("<filename>", "!x!");
var tokens = new TokenIterator<>(
List.of(
token(sourceText, 0, 1, TokenType.SYMBOL),
token(sourceText, 1, 2, TokenType.IDENTIFIER),
token(sourceText, 2, 3, TokenType.SYMBOL)
),
token(sourceText, 3, 3, TokenType.END)
);
assertThat(tokens.peek(0), equalTo(token(sourceText, 0, 1, TokenType.SYMBOL)));
assertThat(tokens.peek(1), equalTo(token(sourceText, 1, 2, TokenType.IDENTIFIER)));
assertThat(tokens.peek(2), equalTo(token(sourceText, 2, 3, TokenType.SYMBOL)));
tokens.skip(TokenType.SYMBOL);
assertThat(tokens.peek(0), equalTo(token(sourceText, 1, 2, TokenType.IDENTIFIER)));
assertThat(tokens.peek(1), equalTo(token(sourceText, 2, 3, TokenType.SYMBOL)));
assertThat(tokens.peek(2), equalTo(token(sourceText, 3, 3, TokenType.END)));
}
private Token<TokenType> token(
SourceText sourceText,
int startCharacterIndex,
int endCharacterIndex,
TokenType tokenType
) {
var start = sourceText.characterPosition(startCharacterIndex);
var end = sourceText.characterPosition(endCharacterIndex);
return new Token<>(start.to(end), tokenType);
}
}
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