Eclipse JDT
Release 3.0

org.eclipse.jdt.core.dom
Class ASTParser

java.lang.Object
  extended byorg.eclipse.jdt.core.dom.ASTParser

public class ASTParser
extends Object

A Java language parser for creating abstract syntax trees (ASTs).

Example: Create basic AST from source string

 char[] source = ...;
 ASTParser parser = ASTParser.newParser(AST.JLS2);  // handles JLS2 (J2SE 1.4)
 parser.setSource(source);
 CompilationUnit result = (CompilationUnit) parser.createAST(null);
 
Once a configured parser instance has been used to create an AST, the settings are automicatically returned to their defaults, ready for the parser instance to be reused.

There are a number of configurable features:

Since:
3.0

Field Summary
static int K_CLASS_BODY_DECLARATIONS
          Kind constant used to request that the source be parsed as a sequence of class body declarations.
static int K_COMPILATION_UNIT
          Kind constant used to request that the source be parsed as a compilation unit.
static int K_EXPRESSION
          Kind constant used to request that the source be parsed as a single expression.
static int K_STATEMENTS
          Kind constant used to request that the source be parsed as a sequence of statements.
 
Method Summary
 ASTNode createAST(org.eclipse.core.runtime.IProgressMonitor monitor)
          Creates an abstract syntax tree.
static ASTParser newParser(int level)
          Creates a new object for creating a Java abstract syntax tree (AST) following the specified set of API rules.
 void setCompilerOptions(Map options)
          Sets the compiler options to be used when parsing.
 void setFocalPosition(int position)
          Requests an abridged abstract syntax tree.
 void setKind(int kind)
          Sets the kind of constructs to be parsed from the source.
 void setProject(IJavaProject project)
          Sets the Java project used when resolving bindings.
 void setResolveBindings(boolean bindings)
          Requests that the compiler should provide binding information for the AST nodes it creates.
 void setSource(char[] source)
          Sets the source code to be parsed.
 void setSource(IClassFile source)
          Sets the source code to be parsed.
 void setSource(ICompilationUnit source)
          Sets the source code to be parsed.
 void setSourceRange(int offset, int length)
          Sets the subrange of the source code to be parsed.
 void setUnitName(String unitName)
          Sets the name of the compilation unit that would hypothetically contains the source string.
 void setWorkingCopyOwner(WorkingCopyOwner owner)
          Sets the working copy owner using when resolving bindings, where null means the primary owner.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

K_EXPRESSION

public static final int K_EXPRESSION
Kind constant used to request that the source be parsed as a single expression.

See Also:
Constant Field Values

K_STATEMENTS

public static final int K_STATEMENTS
Kind constant used to request that the source be parsed as a sequence of statements.

See Also:
Constant Field Values

K_CLASS_BODY_DECLARATIONS

public static final int K_CLASS_BODY_DECLARATIONS
Kind constant used to request that the source be parsed as a sequence of class body declarations.

See Also:
Constant Field Values

K_COMPILATION_UNIT

public static final int K_COMPILATION_UNIT
Kind constant used to request that the source be parsed as a compilation unit.

See Also:
Constant Field Values
Method Detail

newParser

public static ASTParser newParser(int level)
Creates a new object for creating a Java abstract syntax tree (AST) following the specified set of API rules.

NOTE:In Eclipse 3.0, there is no parser support for AST.JLS3. This support is planned for the follow-on release of Eclipse which includes support for J2SE 1.5.

Parameters:
level - the API level; one of the LEVEL constants declared on AST
Returns:
new ASTParser instance

setCompilerOptions

public void setCompilerOptions(Map options)
Sets the compiler options to be used when parsing.

The compiler options default to JavaCore.getOptions().

Parameters:
options - the table of options (key type: String; value type: String), or null to set it back to the default

setResolveBindings

public void setResolveBindings(boolean bindings)
Requests that the compiler should provide binding information for the AST nodes it creates.

Default to false (no bindings).

If setResolveBindings(true), the various names and types appearing in the AST can be resolved to "bindings" by calling the resolveBinding methods. These bindings draw connections between the different parts of a program, and generally afford a more powerful vantage point for clients who wish to analyze a program's structure more deeply. These bindings come at a considerable cost in both time and space, however, and should not be requested frivolously. The additional space is not reclaimed until the AST, all its nodes, and all its bindings become garbage. So it is very important to not retain any of these objects longer than absolutely necessary. Bindings are resolved at the time the AST is created. Subsequent modifications to the AST do not affect the bindings returned by resolveBinding methods in any way; these methods return the same binding as before the AST was modified (including modifications that rearrange subtrees by reparenting nodes). If setResolveBindings(false) (the default), the analysis does not go beyond parsing and building the tree, and all resolveBinding methods return null from the outset.

When bindings are requested, instead of considering compilation units on disk only one can supply a WorkingCopyOwner. Working copies owned by this owner take precedence over the underlying compilation units when looking up names and drawing the connections.

Binding information is obtained from the Java model. This means that the compilation unit must be located relative to the Java model. This happens automatically when the source code comes from either setSource(ICompilationUnit) or setSource(IClassFile). When source is supplied by setSource(char[]), the location must be extablished explicitly by calling setProject(IJavaProject) and setUnitName(String). Note that the compiler options that affect doc comment checking may also affect whether any bindings are resolved for nodes within doc comments.

Parameters:
bindings - true if bindings are wanted, and false if bindings are not of interest

setFocalPosition

public void setFocalPosition(int position)
Requests an abridged abstract syntax tree. By default, complete ASTs are returned. When true the resulting AST does not have nodes for the entire compilation unit. Rather, the AST is only fleshed out for the node that include the given source position. This kind of limited AST is sufficient for certain purposes but totally unsuitable for others. In places where it can be used, the limited AST offers the advantage of being smaller and faster to construct.

The AST will include nodes for all of the compilation unit's package, import, and top-level type declarations. It will also always contain nodes for all the body declarations for those top-level types, as well as body declarations for any member types. However, some of the body declarations may be abridged. In particular, the statements ordinarily found in the body of a method declaration node will not be included (the block will be empty) unless the source position falls somewhere within the source range of that method declaration node. The same is true for initializer declarations; the statements ordinarily found in the body of initializer node will not be included unless the source position falls somewhere within the source range of that initializer declaration node. Field declarations are never abridged. Note that the AST for the body of that one unabridged method (or initializer) is 100% complete; it has all its statements, including any local or anonymous type declarations embedded within them. When the the given position is not located within the source range of any body declaration of a top-level type, the AST returned will be a skeleton that includes nodes for all and only the major declarations; this kind of AST is still quite useful because it contains all the constructs that introduce names visible to the world outside the compilation unit.

Parameters:
position - a position into the corresponding body declaration

setKind

public void setKind(int kind)
Sets the kind of constructs to be parsed from the source. Defaults to an entire compilation unit.

When the parse is successful the result returned includes the ASTs for the requested source:

The resulting AST node is rooted under (possibly contrived) CompilationUnit node, to allow the client to retrieve the following pieces of information available there: The contrived nodes do not have source positions. Other aspects of the CompilationUnit node are unspecified, including the exact arrangment of intervening nodes.

Lexical or syntax errors detected while parsing can result in a result node being marked as MALFORMED. In more severe failure cases where the parser is unable to recognize the input, this method returns a CompilationUnit node with at least the compiler messages.

Each node in the subtree (other than the contrived nodes) carries source range(s) information relating back to positions in the given source (the given source itself is not remembered with the AST). The source range usually begins at the first character of the first token corresponding to the node; leading whitespace and comments are not included. The source range usually extends through the last character of the last token corresponding to the node; trailing whitespace and comments are not included. There are a handful of exceptions (including the various body declarations); the specification for these node type spells out the details. Source ranges nest properly: the source range for a child is always within the source range of its parent, and the source ranges of sibling nodes never overlap.

Binding information is only computed when kind is K_COMPILATION_UNIT.

Parameters:
kind - the kind of construct to parse: one of K_COMPILATION_UNIT, K_CLASS_BODY_DECLARATIONS, K_EXPRESSION, K_STATEMENTS

setSource

public void setSource(char[] source)
Sets the source code to be parsed.

Parameters:
source - the source string to be parsed, or null if none

setSource

public void setSource(ICompilationUnit source)
Sets the source code to be parsed. This method automatically sets the project (and compiler options) based on the given compilation unit, in a manner equivalent to setProject(source.getJavaProject())

Parameters:
source - the Java model compilation unit whose source code is to be parsed, or null if none

setSource

public void setSource(IClassFile source)
Sets the source code to be parsed. This method automatically sets the project (and compiler options) based on the given compilation unit, in a manner equivalent to setProject(source.getJavaProject())

Parameters:
source - the Java model class file whose corresponding source code is to be parsed, or null if none

setSourceRange

public void setSourceRange(int offset,
                           int length)
Sets the subrange of the source code to be parsed. By default, the entire source string will be parsed (offset 0 and length -1).

Parameters:
offset - the index of the first character to parse
length - the number of characters to parse, or -1 if the remainder of the source string is

setWorkingCopyOwner

public void setWorkingCopyOwner(WorkingCopyOwner owner)
Sets the working copy owner using when resolving bindings, where null means the primary owner. Defaults to the primary owner.

Parameters:
owner - the owner of working copies that take precedence over underlying compilation units, or null if the primary owner should be used

setUnitName

public void setUnitName(String unitName)
Sets the name of the compilation unit that would hypothetically contains the source string. This is used in conjunction with setSource(char[]) and setProject to locate the compilation unit relative to a Java project. Defaults to none (null).

The name of the compilation unit must be supplied for resolving bindings. This name should include the ".java" suffix and match the name of the main (public) class or interface declared in the source. For example, if the source declares a public class named "Foo", the name of the compilation should be "Foo.java".

Parameters:
unitName - the name of the compilation unit that would contain the source string, or null if none

setProject

public void setProject(IJavaProject project)
Sets the Java project used when resolving bindings. This method automatically sets the compiler options based on the given project:
 setCompilerOptions(project.getOptions(true));
 
This setting is used in conjunction with setSource(char[]). For the purposes of resolving bindings, types declared in the source string will hide types by the same name available through the classpath of the given project. Defaults to none (null).

Parameters:
project - the Java project used to resolve names, or null if none

createAST

public ASTNode createAST(org.eclipse.core.runtime.IProgressMonitor monitor)
Creates an abstract syntax tree.

A successful call to this method returns all settings to their default values so the object is ready to be reused.

Parameters:
monitor - the progress monitor used to report progress and request cancelation, or null if none
Returns:
an AST node whose type depends on the kind of parse requested, with a fallback to a CompilationUnit in the case of severe parsing errors
Throws:
IllegalStateException - if the settings provided are insufficient, contradictory, or otherwise unsupported

Eclipse JDT
Release 3.0

Copyright (c) IBM Corp. and others 2000, 2004. All Rights Reserved.