Class SimpleExprNode

Object
  ASTNode
      ExprNode
          SimpleExprNode

public class SimpleExprNode
extends ExprNode

An AST node representing a simple expression with syntax "id" or "id(expr,...,expr)". The expression may represent either a function call or a (possibly subscripted) variable reference depending on the declared type of "id".

Nested Class Summary

Nested classes/interfaces inherited from class ASTNode

ASTNode.Opcode

Field Summary

Fields inherited from class ExprNode

column, line, type

Constructor Summary

SimpleExprNode(IdNode id, List<ExprNode> args)
Creates a new SimpleExprNode.

Method Summary

void	codeGen(int reg) Generates code to load the value of this expression into a register.
void	codeGenLValue(int reg) Generates code to load the lvalue of this expression into a register.
boolean	isLValue() Tests whether this SimpleExprNode represents something that may be on the left-hand-side of an assignment, or passed to an OUT or INOUT parameter of a procedure or function.
static boolean	isLValue(ExprNode exp) Convenience function to test whether an arbitrary ExprNode is an LValue.
void	resolveNames(SymbolTable symtab) Resolves all applied uses of identifiers in the tree rooted at this node.
void	resolveTypes(ProcDeclNode proc) Fills in types for all Symbols bound to IdNodes.
void	unparse(PrintWriter p, int level) Prints a source representation of the tree rooted at this node on output stream p.

Methods inherited from class ExprNode

codeGen

Methods inherited from class ASTNode

indent, toString

Methods inherited from class Object

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

Constructor Detail

SimpleExprNode

public SimpleExprNode(IdNode id,
                      List<ExprNode> args)

Creates a new SimpleExprNode.

Parameters:

id - the name of the function or variable.

args - the list of arguments or subscripts. May be a zero-length list, but must not be null.

Method Detail

isLValue

public boolean isLValue()

Tests whether this SimpleExprNode represents something that may be on the left-hand-side of an assignment, or passed to an OUT or INOUT parameter of a procedure or function. Assumes that resolveNames and resolveTypes have already been called on this SimpleExprNode.

Returns:

true if this SimpleExprNode represents an LValue.

isLValue

public static boolean isLValue(ExprNode exp)

Convenience function to test whether an arbitrary ExprNode is an LValue. Assumes that resolveNames and resolveTypes have already been called on all the variables mentioned in exp.

Parameters:

exp - an arbitrary expression.

Returns:

true if the expression represents an LValue.

unparse

public void unparse(PrintWriter p,
                    int level)

Prints a source representation of the tree rooted at this node on output stream p.

Specified by:

unparse in class ASTNode

Parameters:

p - the place to display the output.

level - the number of levels of indentation to use if the output requires more than one line.

resolveNames

public void resolveNames(SymbolTable symtab)

Resolves all applied uses of identifiers in the tree rooted at this node.

Specified by:

resolveNames in class ASTNode

Parameters:

symtab - the symbol table to be used.

resolveTypes

public void resolveTypes(ProcDeclNode proc)

Fills in types for all Symbols bound to IdNodes. Prints error messages as necessary.

Specified by:

resolveTypes in class ASTNode

Parameters:

proc - the smallest enclosing procedure or function declaration.

codeGen

public void codeGen(int reg)

Generates code to load the value of this expression into a register.

Overrides:

codeGen in class ExprNode

Parameters:

reg - the number of the s register where the result should be placed.

codeGenLValue

public void codeGenLValue(int reg)

Generates code to load the lvalue of this expression into a register.

Parameters:

reg - the number of the s register where the result should be placed.