org.scijava.parsington

Class ExpressionParser

java.lang.Object

org.scijava.parsington.ExpressionParser

public class ExpressionParser
extends Object

A parser for mathematical expressions, using Dijkstra's famous shunting-yard algorithm.

It is important to note that this parser does not attempt to evaluate the expression in any way; rather, it only provides the parsed tree according to the desired operators.

Author:

Curtis Rueden

Constructor Summary

Constructors

Constructor and Description
ExpressionParser() Creates an expression parser with the standard set of operators and default separator symbols (, for group elements, ; for statements).
ExpressionParser(BiFunction<ExpressionParser,String,ParseOperation> parseOperationFactory) Creates an expression parser with custom ParseOperation behavior.
ExpressionParser(Collection<? extends Operator> operators) Creates an expression parser with custom operators and default separator symbols (, for group elements, ; for statements).
ExpressionParser(Collection<? extends Operator> operators, String elementSeparator, String statementSeparator) Creates an expression parser with custom operators and separator symbols.
ExpressionParser(Collection<? extends Operator> operators, String elementSeparator, String statementSeparator, BiFunction<ExpressionParser,String,ParseOperation> parseOperationFactory) Creates an expression parser maximally customized to your requirements!
ExpressionParser(String elementSeparator, String statementSeparator) Creates an expression parser with custom separator symbols.

Method Summary

Modifier and Type	Method and Description
String	elementSeparator() Separator symbol between group elements.
List<Operator>	operators() Gets the list of operators available to expressions.
LinkedList<Object>	parsePostfix(String expression) Parses the given mathematical expression into a queue in Reverse Polish notation (i.e., postfix notation).
SyntaxTree	parseTree(String expression) Parses the given mathematical expression into a syntax tree.
String	statementSeparator() Separator symbol between statements.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExpressionParser

public ExpressionParser()

Creates an expression parser with the standard set of operators and default separator symbols (, for group elements, ; for statements).

See Also:

Operators.standardList()

ExpressionParser

public ExpressionParser(Collection<? extends Operator> operators)

Creates an expression parser with custom operators and default separator symbols (, for group elements, ; for statements).

Parameters:

operators - The collection of operators available to expressions.

ExpressionParser

public ExpressionParser(String elementSeparator,
                        String statementSeparator)

Creates an expression parser with custom separator symbols.

Parameters:

elementSeparator - The symbol to use for separating group elements.

statementSeparator - The symbol to use for separating statements.

ExpressionParser

public ExpressionParser(BiFunction<ExpressionParser,String,ParseOperation> parseOperationFactory)

Creates an expression parser with custom ParseOperation behavior. Customizing this behavior allows you to control lower level parsing characteristics, including what character sequences constitute whitespace, literals, variables, operators, group terminators, element separators, and statement separators.

Parameters:

parseOperationFactory - A function producing ParseOperation objects with behavior customized to your requirements. The typical use case is to subclass ParseOperation to override one or more of its parseSomething methods, and then pass MyCustomParseOperation::new for this argument.

ExpressionParser

public ExpressionParser(Collection<? extends Operator> operators,
                        String elementSeparator,
                        String statementSeparator)

Creates an expression parser with custom operators and separator symbols.

Parameters:

operators - The collection of operators available to expressions.

elementSeparator - The symbol to use for separating group elements.

statementSeparator - The symbol to use for separating statements.

ExpressionParser

public ExpressionParser(Collection<? extends Operator> operators,
                        String elementSeparator,
                        String statementSeparator,
                        BiFunction<ExpressionParser,String,ParseOperation> parseOperationFactory)

Creates an expression parser maximally customized to your requirements!

Parameters:

operators - The collection of operators available to expressions.

elementSeparator - The symbol to use for separating group elements.

statementSeparator - The symbol to use for separating statements.

parseOperationFactory - A function producing ParseOperation objects with behavior customized to your requirements. The typical use case is to subclass ParseOperation to override one or more of its parseSomething methods, and then pass MyCustomParseOperation::new for this argument.

Method Detail

parseTree

public SyntaxTree parseTree(String expression)

Parses the given mathematical expression into a syntax tree.

Parameters:

expression - The mathematical expression to parse.

Returns:

Parsed hierarchy of tokens.

Throws:

IllegalArgumentException - if the syntax of the expression is incorrect.

parsePostfix

public LinkedList<Object> parsePostfix(String expression)

Parses the given mathematical expression into a queue in Reverse Polish notation (i.e., postfix notation).

Parameters:

expression - The mathematical expression to parse.

Returns:

Parsed queue of tokens in postfix notation.

Throws:

IllegalArgumentException - if the syntax of the expression is incorrect.

operators

public List<Operator> operators()

Gets the list of operators available to expressions.

Returns:

A read-only view of the operators list.

elementSeparator

public String elementSeparator()

Separator symbol between group elements. The default symbol is comma (,). Example: f(1, 2)

See Also:

ExpressionParser(Collection, String, String)

statementSeparator

public String statementSeparator()

Separator symbol between statements. The default symbol is semicolon (;). Example: x = 1; y = 2; z = x + y

See Also:

ExpressionParser(Collection, String, String)