xyz.avarel.aje

Class Expression

java.lang.Object

xyz.avarel.aje.Expression

public class Expression
extends java.lang.Object

Used to preset values and functions using add(java.lang.String, xyz.avarel.aje.runtime.Obj), compile and compute an AJE expression. All values are stored in the scope. The expression not compiled until the invocation of either compile() or compute() explicitly; AJEException and its derivatives would not be thrown until then.

Constructor Summary

Constructors

Constructor and Description
Expression(AJELexer lexer, Scope scope) Creates an expression based on a stream of tokens from a lexer.
Expression(java.io.Reader reader) Creates an expression based on the character stream from a reader.
Expression(java.io.Reader reader, Scope scope) Creates an expression based on the character stream from a reader.
Expression(java.lang.String script) Creates an expression based on a string.
Expression(java.lang.String script, Scope scope) Creates an expression based on a string.

Method Summary

Modifier and Type	Method and Description
Expression	add(java.lang.String name, Expression object) Declare a variable with the name and the Obj value from the evaluated Expression.
Expression	add(java.lang.String name, Obj object) Declare a variable with the name and the Obj parameter.
Expr	compile() Parse the expression into an AST structure of Expr nodes.
Obj	compute() Compile if this expression has not been already compiled and compute its value.

Methods inherited from class java.lang.Object

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

Constructor Detail

Expression

public Expression(java.lang.String script)

Creates an expression based on a string. The expression uses a copy of the default scope and its values. This constructor is a shortcut for Expression(String, DefaultScope.INSTANCE.copy())

Parameters:

script - The string of AJE expression.

Expression

public Expression(java.io.Reader reader)

Creates an expression based on the character stream from a reader. The expression uses a copy of the default scope and its values. This constructor is a shortcut for Expression(Reader, DefaultScope.INSTANCE.copy())

Parameters:

reader - The reader instance that reads AJE expressions.\

Expression

public Expression(java.lang.String script,
                  Scope scope)

Creates an expression based on a string.

Parameters:

script - The string of AJE expression.

scope - The scope to evaluate the expression from.

Expression

public Expression(java.io.Reader reader,
                  Scope scope)

Creates an expression based on the character stream from a reader.

Parameters:

reader - The reader instance that reads AJE expressions.

scope - The scope to evaluate the expression from.

Expression

public Expression(AJELexer lexer,
                  Scope scope)

Creates an expression based on a stream of tokens from a lexer.

Parameters:

lexer - The lexer object that outputs AJE tokens.

scope - The scope to evaluate the expression from.

Method Detail

add

public Expression add(java.lang.String name,
                      Obj object)

Declare a variable with the name and the Obj parameter.

Parameters:

name - The name of the variable to assign the value to.

object - The Obj value.

Returns:

The current Expression builder instance. Useful for chaining.

add

public Expression add(java.lang.String name,
                      Expression object)

Declare a variable with the name and the Obj value from the evaluated Expression. Note that the Expression parameter has its own Scope and can not access any values of the current expression.

Parameters:

name - The name of the variable to assign the value to.

object - The Expression value which is then computed as an Obj.

Returns:

The current Expression builder instance. Useful for chaining.

compile

public Expr compile()

Parse the expression into an AST structure of Expr nodes.

Returns:

The compiled Expr.

Throws:

SyntaxException - Error during the lexing or parsing process of the expression.

compute

public Obj compute()

Compile if this expression has not been already compiled and compute its value.

Returns:

Returns the computed value of this expression.

Throws:

SyntaxException - Error during the lexing or parsing process of the expression. Thrown by the invocation of compile().

ComputeException - Error during the execution of the expression.