jminusminus

Class JFieldSelection

java.lang.Object

jminusminus.JAST

jminusminus.JStatement

jminusminus.JExpression

jminusminus.JFieldSelection

All Implemented Interfaces:

JLhs

 class JFieldSelection
extends JExpression
implements JLhs

The AST node for a field selection operation. It has a target object, a field name, and the Field it defines.

Field Summary

Fields

Modifier and Type	Field and Description
protected JExpression	target The target expression.

Fields inherited from class jminusminus.JExpression

isStatementExpression, type

Fields inherited from class jminusminus.JAST

compilationUnit, line

Constructor Summary

Constructors

Constructor and Description
JFieldSelection(int line, AmbiguousName ambiguousPart, JExpression target, String fieldName) Construct an AST node for a field selection having an ambiguous part.
JFieldSelection(int line, JExpression target, String fieldName) Construct an AST node for a field selection without an ambiguous part.

Method Summary

Methods

Modifier and Type	Method and Description
JExpression	analyze(Context context) Analyzing a field selection expression involves, (1) reclassifying any ambiguous part, (2) analyzing the target, (3) treating "length" field of arrays specially, or computing the Field object, (4) checking the access rules, and (5) computing the resultant type.
JExpression	analyzeLhs(Context context) Analyze the field selection expression for use on the lhs of an assignment.
void	codegen(CLEmitter output) Generate the code necessary to load the Rvalue for this field selection.
void	codegen(CLEmitter output, String targetLabel, boolean onTrue) The semantics of j-- require that we implement short-circuiting branching in implementing field selections.
void	codegenDuplicateRvalue(CLEmitter output) Generate the code required for duplicating the Rvalue that is on the stack becuase it is to be used in a surrounding expression, as in a[i] = x = or x = y--.
void	codegenLoadLhsLvalue(CLEmitter output) Generate the code required for setting up an Lvalue, eg, for use in an assignment.
void	codegenLoadLhsRvalue(CLEmitter output) Generate the code required for loading an Rvalue for this variable, eg for use in a +=.
void	codegenStore(CLEmitter output) Generate the code required for doing the actual assignment.
void	writeToStdOut(PrettyPrinter p) Write the information pertaining to this AST to STDOUT.

Methods inherited from class jminusminus.JExpression

isStatementExpression, type

Methods inherited from class jminusminus.JAST

line, partialCodegen

Methods inherited from class java.lang.Object

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

Field Detail

target

protected JExpression target

The target expression.

Constructor Detail

JFieldSelection

public JFieldSelection(int line,
               JExpression target,
               String fieldName)

Construct an AST node for a field selection without an ambiguous part.

Parameters:

line - the line number of the selection.

target - the target of the selection.

fieldName - the field name.

JFieldSelection

public JFieldSelection(int line,
               AmbiguousName ambiguousPart,
               JExpression target,
               String fieldName)

Construct an AST node for a field selection having an ambiguous part.

Parameters:

line - line in which the field selection occurs in the source file.

ambiguousPart - the ambiguous part.

target - the target of the selection.

fieldName - the field name.

Method Detail

analyze

public JExpression analyze(Context context)

Analyzing a field selection expression involves, (1) reclassifying any ambiguous part, (2) analyzing the target, (3) treating "length" field of arrays specially, or computing the Field object, (4) checking the access rules, and (5) computing the resultant type.

Specified by:

analyze in class JExpression

Parameters:

context - context in which names are resolved.

Returns:

the analyzed (and possibly rewritten) AST subtree.

analyzeLhs

public JExpression analyzeLhs(Context context)

Analyze the field selection expression for use on the lhs of an assignment. Although the final keyword is not in j--, we do make use of the Java api and so must repect its constraints.

Specified by:

analyzeLhs in interface JLhs

Parameters:

context - context in which names are resolved.

Returns:

the analyzed (and possibly rewritten) AST subtree.

codegen

public void codegen(CLEmitter output)

Generate the code necessary to load the Rvalue for this field selection.

Specified by:

codegen in class JAST

Parameters:

output - the code emitter (basically an abstraction for producing the .class file).

codegen

public void codegen(CLEmitter output,
           String targetLabel,
           boolean onTrue)

The semantics of j-- require that we implement short-circuiting branching in implementing field selections.

Overrides:

codegen in class JExpression

Parameters:

output - the code emitter (basically an abstraction for producing the .class file).

targetLabel - the label to which we should branch.

onTrue - do we branch on true?

codegenLoadLhsLvalue

public void codegenLoadLhsLvalue(CLEmitter output)

Generate the code required for setting up an Lvalue, eg, for use in an assignment.

Specified by:

codegenLoadLhsLvalue in interface JLhs

Parameters:

output - the code emitter (basically an abstraction for producing the .class file).

codegenLoadLhsRvalue

public void codegenLoadLhsRvalue(CLEmitter output)

Generate the code required for loading an Rvalue for this variable, eg for use in a +=. Here, this requires either a getstatic or getfield.

Specified by:

codegenLoadLhsRvalue in interface JLhs

Parameters:

output - the code emitter (basically an abstraction for producing the .class file).

codegenDuplicateRvalue

public void codegenDuplicateRvalue(CLEmitter output)

Generate the code required for duplicating the Rvalue that is on the stack becuase it is to be used in a surrounding expression, as in a[i] = x = or x = y--. Here this means copying it down

Specified by:

codegenDuplicateRvalue in interface JLhs

Parameters:

output - the code emitter (basically an abstraction for producing the .class file).

codegenStore

public void codegenStore(CLEmitter output)

Generate the code required for doing the actual assignment.

Specified by:

codegenStore in interface JLhs

Parameters:

output - the code emitter (basically an abstraction for producing the .class file).

writeToStdOut

public void writeToStdOut(PrettyPrinter p)

Description copied from class: JAST

Write the information pertaining to this AST to STDOUT.

Specified by:

writeToStdOut in class JAST

Parameters:

p - for pretty printing with indentation.