jminusminus

Class JVariable

java.lang.Object

jminusminus.JAST

jminusminus.JStatement

jminusminus.JExpression

jminusminus.JVariable

All Implemented Interfaces:

JLhs

 class JVariable
extends JExpression
implements JLhs

The AST node for an identifier used as a primary expression.

Field Summary

Fields inherited from class jminusminus.JExpression

isStatementExpression, type

Fields inherited from class jminusminus.JAST

compilationUnit, line

Constructor Summary

Constructors

Constructor and Description
JVariable(int line, String name) Construct the AST node for a variable given its line number and name.

Method Summary

Methods

Modifier and Type	Method and Description
JExpression	analyze(Context context) Analyzing identifiers involves resolving them in the context.
JExpression	analyzeLhs(Context context) Analyze the identifier as used on the lhs of an assignment.
void	codegen(CLEmitter output) Generate code to load value of variable on stack.
void	codegen(CLEmitter output, String targetLabel, boolean onTrue) The semantics of j-- require that we implement short-circuiting branching in implementing the identifier expression.
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.
IDefn	iDefn() Return the identifier's definition.
String	name() Return the identifier name.
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

Constructor Detail

JVariable

public JVariable(int line,
         String name)

Construct the AST node for a variable given its line number and name.

Parameters:

line - line in which the variable occurs in the source file.

name - the name.

Method Detail

name

public String name()

Return the identifier name.

Returns:

the identifier name.

iDefn

public IDefn iDefn()

Return the identifier's definition.

Returns:

the identifier's definition.

analyze

public JExpression analyze(Context context)

Analyzing identifiers involves resolving them in the context. Identifiers denoting fileds (with implicit targets) are rewritten as explicit field selection operations.

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 identifier as used on the lhs of an assignment.

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 code to load value of variable on stack.

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 the identifier expression.

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. Here, this requires nothing; all information is in the the store instruction.

Specified by:

codegenLoadLhsLvalue in interface JLhs

Parameters:

output - the emitter (an abstraction of 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 loading the Rvalue for the variable

Specified by:

codegenLoadLhsRvalue in interface JLhs

Parameters:

output - the emitter (an abstraction of 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 simply duplicating the value on the stack.

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. Here, this requires storing what's on the stack at the appropriate offset.

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.