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Add isNext(char) and isNext(Predicate<Character>) methods to ImmutableStringReader and StringReader #98

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Add isNext(char) and isNext(Predicate<Character>) methods to ImmutableStringReader and StringReader #98

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a048014
Add isAt method to ImmutableStringReader and StringReader
ErrorCraft Jul 25, 2021
1175816
Rename isAt method to isNext in ImmutableStringReader and StringReader
ErrorCraft Jul 29, 2021
6d62cc1
Add isAt(Predicate<Character>) method to ImmutableStringReader and St…
ErrorCraft Aug 8, 2021
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6 changes: 6 additions & 0 deletions src/main/java/com/mojang/brigadier/ImmutableStringReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@

package com.mojang.brigadier;

import java.util.function.Predicate;

public interface ImmutableStringReader {
String getString();

Expand All @@ -23,4 +25,8 @@ public interface ImmutableStringReader {
char peek();

char peek(int offset);

boolean isNext(char c);

boolean isNext(Predicate<Character> predicate);
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@Marcono1234 Marcono1234 Nov 25, 2021 •
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What about using IntPredicate here? This would avoid boxing and unboxing. But maybe it does not matter much. And it might cause confusion, making users believe this handles code points (including > Character.MAX_VALUE), so this would require renaming the parameter to for example charPredicate.

}
26 changes: 19 additions & 7 deletions src/main/java/com/mojang/brigadier/StringReader.java
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Expand Up @@ -5,6 +5,8 @@

import com.mojang.brigadier.exceptions.CommandSyntaxException;

import java.util.function.Predicate;

public class StringReader implements ImmutableStringReader {
private static final char SYNTAX_ESCAPE = '\\';
private static final char SYNTAX_DOUBLE_QUOTE = '"';
Expand Down Expand Up @@ -76,6 +78,16 @@ public char peek(final int offset) {
return string.charAt(cursor + offset);
}

@Override
public boolean isNext(char c) {
return canRead() && peek() == c;
}

@Override
public boolean isNext(Predicate<Character> predicate) {
return canRead() && predicate.test(peek());
}
Comment on lines +81 to +89
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Would it make sense to implement these as default methods of the interface instead?
(Though assuming no or only a few users implement their own ImmutableStringReader it likely makes no difference)


public char read() {
return string.charAt(cursor++);
}
Expand All @@ -93,14 +105,14 @@ public static boolean isQuotedStringStart(char c) {
}

public void skipWhitespace() {
while (canRead() && Character.isWhitespace(peek())) {
while (isNext(Character::isWhitespace)) {
skip();
}
}

public int readInt() throws CommandSyntaxException {
final int start = cursor;
while (canRead() && isAllowedNumber(peek())) {
while (isNext(StringReader::isAllowedNumber)) {
skip();
}
final String number = string.substring(start, cursor);
Expand All @@ -117,7 +129,7 @@ public int readInt() throws CommandSyntaxException {

public long readLong() throws CommandSyntaxException {
final int start = cursor;
while (canRead() && isAllowedNumber(peek())) {
while (isNext(StringReader::isAllowedNumber)) {
skip();
}
final String number = string.substring(start, cursor);
Expand All @@ -134,7 +146,7 @@ public long readLong() throws CommandSyntaxException {

public double readDouble() throws CommandSyntaxException {
final int start = cursor;
while (canRead() && isAllowedNumber(peek())) {
while (isNext(StringReader::isAllowedNumber)) {
skip();
}
final String number = string.substring(start, cursor);
Expand All @@ -151,7 +163,7 @@ public double readDouble() throws CommandSyntaxException {

public float readFloat() throws CommandSyntaxException {
final int start = cursor;
while (canRead() && isAllowedNumber(peek())) {
while (isNext(StringReader::isAllowedNumber)) {
skip();
}
final String number = string.substring(start, cursor);
Expand All @@ -176,7 +188,7 @@ public static boolean isAllowedInUnquotedString(final char c) {

public String readUnquotedString() {
final int start = cursor;
while (canRead() && isAllowedInUnquotedString(peek())) {
while (isNext(StringReader::isAllowedInUnquotedString)) {
skip();
}
return string.substring(start, cursor);
Expand Down Expand Up @@ -249,7 +261,7 @@ public boolean readBoolean() throws CommandSyntaxException {
}

public void expect(final char c) throws CommandSyntaxException {
if (!canRead() || peek() != c) {
if (!isNext(c)) {
throw CommandSyntaxException.BUILT_IN_EXCEPTIONS.readerExpectedSymbol().createWithContext(this, String.valueOf(c));
}
skip();
Expand Down
24 changes: 24 additions & 0 deletions src/test/java/com/mojang/brigadier/StringReaderTest.java
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Expand Up @@ -6,6 +6,8 @@
import com.mojang.brigadier.exceptions.CommandSyntaxException;
import org.junit.Test;

import java.util.function.Predicate;

import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.is;
import static org.junit.Assert.assertThat;
Expand Down Expand Up @@ -585,4 +587,26 @@ public void readBoolean_none() throws Exception {
assertThat(ex.getCursor(), is(0));
}
}

@Test
public void isNext() {
final StringReader reader = new StringReader("abc");
assertThat(reader.isNext('a'), is(true));
assertThat(reader.isNext('x'), is(false));
reader.setCursor(2);
assertThat(reader.isNext('c'), is(true));
reader.skip();
assertThat(reader.isNext('c'), is(false));
}

@Test
public void isNext_predicate() {
final StringReader reader = new StringReader("abc");
final Predicate<Character> predicate = c -> (c == 'a' || c == 'b');
assertThat(reader.isNext(predicate), is(true));
reader.setCursor(1);
assertThat(reader.isNext(predicate), is(true));
reader.setCursor(2);
assertThat(reader.isNext(predicate), is(false));
}
}