/
ExamplesTest.java
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/
ExamplesTest.java
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package org.petitparser;
import org.junit.Test;
import org.petitparser.parser.Parser;
import org.petitparser.parser.combinators.SettableParser;
import org.petitparser.tools.ExpressionBuilder;
import java.util.List;
import java.util.function.Function;
import static org.petitparser.Assertions.assertFailure;
import static org.petitparser.Assertions.assertSuccess;
import static org.petitparser.parser.primitive.CharacterParser.any;
import static org.petitparser.parser.primitive.CharacterParser.digit;
import static org.petitparser.parser.primitive.CharacterParser.letter;
import static org.petitparser.parser.primitive.CharacterParser.of;
import static org.petitparser.parser.primitive.CharacterParser.whitespace;
import static org.petitparser.parser.primitive.CharacterParser.word;
import static org.petitparser.parser.primitive.StringParser.of;
/**
* Tests some small but realistic parser examples.
*/
public class ExamplesTest {
public static final Parser IDENTIFIER = letter().seq(word().star()).flatten();
public static final Parser NUMBER = of('-').optional()
.seq(digit().plus())
.seq(of('.').seq(digit().plus()).optional())
.flatten();
public static final Parser STRING = of('"')
.seq(any().starLazy(of('"')))
.seq(of('"'))
.flatten();
public static final Parser RETURN = of("return")
.seq(whitespace().plus().flatten())
.seq(IDENTIFIER.or(NUMBER).or(STRING))
.pick(-1);
public static final Parser JAVADOC = of("/**")
.seq(any().starLazy(of("*/")))
.seq(of("*/"))
.flatten();
public static final Parser DOUBLE = digit().plus().seq(of('.')
.seq(digit().plus()).optional())
.flatten().trim().map(Double::parseDouble);
@Test
public void testIdentifierSuccess() {
assertSuccess(IDENTIFIER, "a", "a");
assertSuccess(IDENTIFIER, "a1", "a1");
assertSuccess(IDENTIFIER, "a12", "a12");
assertSuccess(IDENTIFIER, "ab", "ab");
assertSuccess(IDENTIFIER, "a1b", "a1b");
}
@Test
public void testIdentifierIncomplete() {
assertSuccess(IDENTIFIER, "a_", "a", 1);
assertSuccess(IDENTIFIER, "a1-", "a1", 2);
assertSuccess(IDENTIFIER, "a12+", "a12", 3);
assertSuccess(IDENTIFIER, "ab ", "ab", 2);
}
@Test
public void testIdentifierFailure() {
assertFailure(IDENTIFIER, "", "letter expected");
assertFailure(IDENTIFIER, "1", "letter expected");
assertFailure(IDENTIFIER, "1a", "letter expected");
}
@Test
public void testNumberPositiveSuccess() {
assertSuccess(NUMBER, "1", "1");
assertSuccess(NUMBER, "12", "12");
assertSuccess(NUMBER, "12.3", "12.3");
assertSuccess(NUMBER, "12.34", "12.34");
}
@Test
public void testNumberNegativeSuccess() {
assertSuccess(NUMBER, "-1", "-1");
assertSuccess(NUMBER, "-12", "-12");
assertSuccess(NUMBER, "-12.3", "-12.3");
assertSuccess(NUMBER, "-12.34", "-12.34");
}
@Test
public void testNumberIncomplete() {
assertSuccess(NUMBER, "1..", "1", 1);
assertSuccess(NUMBER, "12-", "12", 2);
assertSuccess(NUMBER, "12.3.", "12.3", 4);
assertSuccess(NUMBER, "12.34.", "12.34", 5);
}
@Test
public void testNumberFailure() {
assertFailure(NUMBER, "", "digit expected");
assertFailure(NUMBER, "-", 1, "digit expected");
assertFailure(NUMBER, "-x", 1, "digit expected");
assertFailure(NUMBER, ".", "digit expected");
assertFailure(NUMBER, ".1", "digit expected");
}
@Test
public void testStringSuccess() {
assertSuccess(STRING, "\"\"", "\"\"");
assertSuccess(STRING, "\"a\"", "\"a\"");
assertSuccess(STRING, "\"ab\"", "\"ab\"");
assertSuccess(STRING, "\"abc\"", "\"abc\"");
}
@Test
public void testStringIncomplete() {
assertSuccess(STRING, "\"\"x", "\"\"", 2);
assertSuccess(STRING, "\"a\"x", "\"a\"", 3);
assertSuccess(STRING, "\"ab\"x", "\"ab\"", 4);
assertSuccess(STRING, "\"abc\"x", "\"abc\"", 5);
}
@Test
public void testStringFailure() {
assertFailure(STRING, "\"", 1, "'\"' expected");
assertFailure(STRING, "\"a", 2, "'\"' expected");
assertFailure(STRING, "\"ab", 3, "'\"' expected");
assertFailure(STRING, "a\"", "'\"' expected");
assertFailure(STRING, "ab\"", "'\"' expected");
}
@Test
public void testReturnSuccess() {
assertSuccess(RETURN, "return f", "f");
assertSuccess(RETURN, "return f", "f");
assertSuccess(RETURN, "return foo", "foo");
assertSuccess(RETURN, "return foo", "foo");
assertSuccess(RETURN, "return 1", "1");
assertSuccess(RETURN, "return 1", "1");
assertSuccess(RETURN, "return -2.3", "-2.3");
assertSuccess(RETURN, "return -2.3", "-2.3");
assertSuccess(RETURN, "return \"a\"", "\"a\"");
assertSuccess(RETURN, "return \"a\"", "\"a\"");
}
@Test
public void testReturnFailure() {
assertFailure(RETURN, "retur f", 0, "return expected");
assertFailure(RETURN, "return1", 6, "whitespace expected");
assertFailure(RETURN, "return $", 8, "'\"' expected");
}
@Test
public void testJavaDoc() {
assertSuccess(JAVADOC, "/** foo */", "/** foo */");
assertSuccess(JAVADOC, "/** * * */", "/** * * */");
}
@Test
public void testExpression() {
Parser number = digit().plus().flatten().trim()
.map((Function<String, Integer>) Integer::parseInt);
SettableParser term = SettableParser.undefined();
SettableParser prod = SettableParser.undefined();
SettableParser prim = SettableParser.undefined();
term.set(prod.seq(of('+').trim())
.seq(term)
.map((List<Integer> values) -> values.get(0) + values.get(2))
.or(prod));
prod.set(prim.seq(of('*').trim())
.seq(prod)
.map((List<Integer> values) -> values.get(0) * values.get(2))
.or(prim));
prim.set((of('(').trim().seq(term).seq(of(')').trim()))
.map((List<Integer> values) -> values.get(1))
.or(number));
Parser start = term.end();
assertSuccess(start, "1 + 2 * 3", 7);
assertSuccess(start, "(1 + 2) * 3", 9);
}
@Test
public void testExpressionBuilderWithSettableExample() throws Exception {
SettableParser recursion = SettableParser.undefined();
Parser bracket = of('(')
.seq(recursion)
.seq(of(')')).map((List<Double> values) -> values.get(1));
ExpressionBuilder builder = new ExpressionBuilder();
builder.group()
.primitive(bracket.or(DOUBLE));
initOperators(builder);
recursion.set(builder.build());
Parser parser = recursion.end();
assertCalculatorExample(parser);
}
@Test
public void testExpressionBuilderWithWrapperExample() throws Exception {
ExpressionBuilder builder = new ExpressionBuilder();
builder.group()
.primitive(DOUBLE)
.wrapper(of('(').trim(), of(')').trim(),
(List<Double> values) -> values.get(1));
initOperators(builder);
Parser parser = builder.build().end();
assertCalculatorExample(parser);
}
private void initOperators(ExpressionBuilder builder) {
// negation is a prefix operator
builder.group()
.prefix(of('-').trim(), (List<Double> values) -> -values.get(1));
// power is right-associative
builder.group()
.right(of('^').trim(),
(List<Double> values) -> Math.pow(values.get(0), values.get(2)));
// multiplication and addition are left-associative
builder.group()
.left(of('*').trim(),
(List<Double> values) -> values.get(0) * values.get(2))
.left(of('/').trim(),
(List<Double> values) -> values.get(0) / values.get(2));
builder.group()
.left(of('+').trim(),
(List<Double> values) -> values.get(0) + values.get(2))
.left(of('-').trim(),
(List<Double> values) -> values.get(0) - values.get(2));
}
private void assertCalculatorExample(Parser parser) {
Parser intCalculator = parser.map(Double::intValue);
assertSuccess(intCalculator, "-8", -8);
assertSuccess(intCalculator, "1+2*3", 7);
assertSuccess(intCalculator, "1*2+3", 5);
assertSuccess(intCalculator, "8/4/2", 1);
assertSuccess(intCalculator, "2^2^3", 256);
}
}