boolparser

A Boolean Expression Parser

The library can help parse complex and nested boolean expressions. The filter expression is SQL-like syntax, where you can use boolean operators and parentheses to combine individual filters.

Textual Equality

Format: ${attributeName}:${value}

Example: name:john

Numeric Comparisons

Format: ${attributeName} ${operator} ${value}

Example: price > 12.99

The ${value} must be numeric. Supported operators are <, <=, =, !=, >= and >, with the same semantics as in virtually all programming languages.

Numeric Range

Format: ${attributeName}:${lowerBound} TO ${upperBound}

Example: price:5.99 TO 100

${lowerBound} and ${upperBound} must be numeric. Both are inclusive.

Boolean operators

Example:

price < 10 AND (category:Book OR NOT category:Ebook)

Individual filters can be combined via boolean operators. The following operators are supported:

• OR: must match any of the combined conditions (disjunction)
• AND: must match all of the combined conditions (conjunction)
• NOT: negate a filter

Parentheses, ( and ), can be used for grouping.

You cannot negate a group of filters, only an individual filter. For example, NOT(filter1 OR filter2) is not allowed.

Usage Notes

• Phrases that includes quotes, like content:"It's a wonderful day"
• Phrases that includes quotes, like attribute:'She said "Hello World"'

Usage

POM

    <dependencies>
        <dependency>
            <groupId>com.github.sidhant92</groupId>
            <artifactId>boolparser</artifactId>
            <version>1.0.0</version>
        </dependency>
    </dependencies>

Gradle

dependencies {
	implementation "com.github.sidhant92:boolparser:1.0.3"
}

final PEGBoolExpressionParser boolExpressionParser = new PEGBoolExpressionParser();
final Optional<Node> nodeOptional = boolExpressionParser.parseExpression("name:test");

Node Types

StringToken

private final String field;

private final String value;

NumericToken

private final String field;

private final Object value;

private final Operator operator;

private final DataType dataType;

NumericRangeToken

private final String field;

private final Object fromValue;

private final Object toValue;

private final DataType fromDataType;

private final DataType toDataType;

BoolExpression

private final List<Node> orOperations = new ArrayList<>();

private final List<Node> andOperations = new ArrayList<>();

private final List<Node> notOperations = new ArrayList<>();

Applications

Boolean Expression Evaluator

The library can be used to evaluate a boolean expression.

The following Data Types are supported:

1. String
2. Integers
3. Decimals
4. Boolean
5. App Version

Usage examples:

Simple Numerical Comparison

final BooleanExpressionEvaluator booleanExpressionEvaluator = new BooleanExpressionEvaluator();
final Map<String, Object> data = new HashMap<>();
data.put("age", 26);
final Optional<Boolean> booleanOptional = booleanExpressionEvaluator.evaluate("age >= 27", data);
assertTrue(booleanOptional.isPresent());
assertFalse(booleanOptional.get());

Boolean Comparison

final BooleanExpressionEvaluator booleanExpressionEvaluator = new BooleanExpressionEvaluator();
final Map<String, Object> data = new HashMap<>();
data.put("age", 25);
data.put("name", "sid");
final Optional<Boolean> booleanOptional = booleanExpressionEvaluator.evaluate("name:sid AND age = 25", data);
assertTrue(booleanOptional.isPresent());
assertTrue(booleanOptional.get());

Nested Boolean Comparison

final BooleanExpressionEvaluator booleanExpressionEvaluator = new BooleanExpressionEvaluator();
final Map<String, Object> data = new HashMap<>();
data.put("age", 25);
data.put("name", "sid");
data.put("num", 45);
final Optional<Boolean> booleanOptional = booleanExpressionEvaluator.evaluate("name:sid AND (age = 25 OR num = 44)", data);
assertTrue(booleanOptional.isPresent());
assertTrue(booleanOptional.get());

App Version Comparison

final BooleanExpressionEvaluator booleanExpressionEvaluator = new BooleanExpressionEvaluator();
final Map<String, Object> data = new HashMap<>();
data.put("app_version", "1.5.9");
final Optional<Boolean> booleanOptional = booleanExpressionEvaluator.evaluate("app_version < 1.5.10", data);
assertTrue(booleanOptional.isPresent());
assertTrue(booleanOptional.get());

The return type is Optional<Boolean>. If its absent which means parsing has failed and any fallback can be used.

For a complete list of examples please check out the test file