gnu.expr

Class Expression

public abstract class Expression extends Procedure0 implements Printable, SourceLocator

Abstract class for syntactic forms that evaluate to a value. Scheme S-expressions get re-written to these before evaluation.

Field Summary
protected int	flags
static Expression[]	noExpressions
protected static int	NEXT_AVAIL_FLAG

Method Summary
void	apply(CallContext ctx) Evaluate the expression.
Object	apply0()
abstract void	compile(Compilation comp, Target target)
void	compile(Compilation comp, Type type)
void	compile(Compilation comp, Declaration lhs) Compile an expression with checking suitable for a known Declaration.
static void	compileButFirst(Expression exp, Compilation comp) Compile all but the first sub-"statement".
void	compileNotePosition(Compilation comp, Target target, Expression position) Compile, but take note of line number.
void	compileWithPosition(Compilation comp, Target target) Same as compile, but emit line number beforehard.
void	compileWithPosition(Compilation comp, Target target, Expression position) Same as 2-argument compileWithPosition, but use some other Expression's line number.
Object	eval(CallContext ctx)
Object	eval(Environment env)
int	getColumnNumber()
String	getFileName()
boolean	getFlag(int flag)
int	getFlags()
int	getLineNumber() Get the line number of (the start of) this Expression.
String	getPublicId()
String	getSystemId()
Type	getType() Return the Type used to represent the values of this Expression.
Expression	inline(ApplyExp exp, InlineCalls walker, Declaration decl) Apply inlining transformations on a given ApplyExp.
boolean	isStableSourceLocation()
static Expression	makeWhile(Object cond, Object body, Compilation parser) Helper method to create a `while' statement.
int	match0(CallContext ctx)
protected abstract boolean	mustCompile()
void	print(Consumer out)
abstract void	print(OutPort ps)
void	printLineColumn(OutPort out) Print line and column number if specified.
void	setFile(String filename)
void	setFlag(boolean setting, int flag)
void	setFlag(int flag)
Expression	setLine(Expression old)
void	setLine(int lineno, int colno)
void	setLine(int lineno)
void	setLine(Compilation comp) Set line number from current position in `Compilation`.
void	setLocation(SourceLocator location) Copies the current location.
boolean	side_effects() True if evaluating may have side-effects.
String	toString()
Object	valueIfConstant() Return value if it is constant, or null if non-constant or unknown.
protected Expression	walk(ExpWalker walker)
protected void	walkChildren(ExpWalker walker)

Field Detail

noExpressions

public static final Expression[] noExpressions

NEXT_AVAIL_FLAG

protected static final int NEXT_AVAIL_FLAG

Evaluate the expression. This is named apply rather than eval so it is compatible with the full-tail-call calling convention, and we can stash an Expression in CallContext's proc field. FIXME - are we making use of this?

apply0

public final Object apply0()

compile

public abstract void compile(Compilation comp, Target target)

compile

public final void compile(Compilation comp, Type type)

compile

public final void compile(Compilation comp, Declaration lhs)

Compile an expression with checking suitable for a known Declaration. Leaves the result on the stack (i.e. does not assign to the lhs). It does coerce the value to a suitable type for the lhs, and throw a hopefully-informative WrongType exception on failure.

compileButFirst

public static void compileButFirst(Expression exp, Compilation comp)

Compile all but the first sub-"statement". A kludge used for constructor methods, since if the first "statement" is a super-constructor we need to inject initializer expressions.

compileNotePosition

public final void compileNotePosition(Compilation comp, Target target, Expression position)

Compile, but take note of line number.

compileWithPosition

public final void compileWithPosition(Compilation comp, Target target)

Same as compile, but emit line number beforehard.

compileWithPosition

public final void compileWithPosition(Compilation comp, Target target, Expression position)

Same as 2-argument compileWithPosition, but use some other Expression's line number.

eval

public final Object eval(CallContext ctx)

eval

public final Object eval(Environment env)

getColumnNumber

public final int getColumnNumber()

getFileName

public final String getFileName()

getFlag

public boolean getFlag(int flag)

getFlags

public int getFlags()

getLineNumber

public final int getLineNumber()

Get the line number of (the start of) this Expression. The "first" line is line 1; unknown is -1.

getPublicId

public String getPublicId()

getSystemId

public String getSystemId()

getType

public Type getType()

Return the Type used to represent the values of this Expression.

inline

public Expression inline(ApplyExp exp, InlineCalls walker, Declaration decl)

Apply inlining transformations on a given ApplyExp. Assumes the ApplyExp's function is the this expression, or can be optimized to this expression.

Parameters: exp an application whose function expression can be simplified to this expression. walker the context for the current inlining pass decl if non-null, a Declaration bound to this expression

Returns: an Expression equivalent to te passed-in exp.