org.erights.e.elang.evm
Class EExpr

java.lang.Object
  |
  +--org.erights.e.elang.evm.ParseNode
        |
        +--org.erights.e.elang.evm.ENode
              |
              +--org.erights.e.elang.evm.EExpr

All Implemented Interfaces:

Cloneable, EPrintable, MatchMaker

Direct Known Subclasses:

AssignExpr, AtomicExpr, CallExpr, CatchExpr, DefineExpr, EscapeExpr, FinallyExpr, HideExpr, IfExpr, LiteralExpr, MatchBindExpr, ObjectExpr, ScopeExpr, SendExpr, SeqExpr, SlotExpr, SmallcapsExpr

public abstract class EExpr

extends ENode

Untamed: Those ParseNodes that--after expansion--define the kernel expressions evaluated by the E Virtual Machine.

Author:

Mark S. Miller, E. Dean Tribble

Field Summary

Fields inherited from class org.erights.e.elang.evm.ENode

Fields inherited from class org.erights.e.elang.evm.ParseNode

NUM_PR, PR_ASSIGN, PR_CALL, PR_COMP, PR_EEXPR, PR_LISTPATT, PR_ORDER, PR_PATTERN, PR_PRIM, PR_START

Constructor Summary

protected

EExpr(SourceSpan optSpan)

Method Summary

void	__printOn(TextWriter out) Enabled: @see #subPrintOn
(package private) static void	appendAllTo(FlexList accum, EExpr[] all) Recursively append all the supplied nodes to accum.
(package private) void	appendTo(FlexList accum) Append the sequence of operations representated by this node to the argument.
static Object	eval(EExpr self, Scope scope, int maxLocals) Enabled: To be invoked only on a Transformed-E expression to do the actual evaluation.
Object	eval(Scope scope) Enabled: Used to evaluate this expression to a value in scope.
(package private) boolean	evalBool(EvalContext ctx) Like subEval, but returns the result coerced to a boolean.
void	printAsBlockOn(TextWriter out) Enabled:
protected abstract Object	subEval(EvalContext ctx, boolean forValue) The recursive part that does the work
EExpr	substitute(ConstList args) Enabled:
static Object[]	transform(EExpr self, Scope scope) Enabled: Transforms from Expanded-E or Kernel-E to the internal Transformed-E.

Methods inherited from class org.erights.e.elang.evm.ENode

cleanCopy, computeStaticScope, copy, getOptPatternMap, getOptScopeMap, getPatternMap, getScopeMap, qbuild, setPatternMap, setScopeMap, staticScope, synEnv, welcome

Methods inherited from class org.erights.e.elang.evm.ParseNode

asText, getOptSpan, lnPrintOn, lnPrintOn, matchBind, matchBind, matchBind, matchBind, printListOn, subPrintOn, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

EExpr

protected EExpr(SourceSpan optSpan)

Method Detail

__printOn

public void __printOn(TextWriter out)
               throws IOException

Enabled: @see #subPrintOn

Specified by:

__printOn in interface EPrintable

Overrides:

__printOn in class ParseNode

IOException

See Also:

ParseNode.subPrintOn(org.erights.e.elib.oldeio.TextWriter, int)

substitute

public EExpr substitute(ConstList args)

Enabled:

transform

public static Object[] transform(EExpr self,
                                 Scope scope)

Enabled: Transforms from Expanded-E or Kernel-E to the internal Transformed-E.

The transform method is factored out from eval so that the interpreter loop can print the transformed expression for debugging purposes.

XXX This should be changed to only take a scopeMap as argument instead, so that the [Expanded-E, ScopeMap] => Transformed-E mapping can be memoized. Once we compile Transformed-E to JVM bytecodes, this will allow us to cache the class files and classes as well.

Returns:

A pair of a Transformed-E expression and the number of locals it needs to evaluate.

eval

public static Object eval(EExpr self,
                          Scope scope,
                          int maxLocals)

Enabled: To be invoked only on a Transformed-E expression to do the actual evaluation.

This is the rest of eval/1 after factoring out transform/2, and is likewise public only for debugging purposes.

XXX We need to enforce that this is only invoked on a Transformed-E expression. The Transformed-E EExpr should probably remember the number of locals it needs, so we don't have to worry about a bad value being passed in.

eval

public Object eval(Scope scope)

Enabled: Used to evaluate this expression to a value in scope.

subEval

protected abstract Object subEval(EvalContext ctx,
                                  boolean forValue)

The recursive part that does the work

evalBool

boolean evalBool(EvalContext ctx)

Like subEval, but returns the result coerced to a boolean.

printAsBlockOn

public void printAsBlockOn(TextWriter out)
                    throws IOException

Enabled:

IOException

appendTo

void appendTo(FlexList accum)

Append the sequence of operations representated by this node to the argument.

Parameters:

accum -

appendAllTo

static void appendAllTo(FlexList accum,
                        EExpr[] all)

Recursively append all the supplied nodes to accum.

Parameters:

accum - the List to accumulate the results into.

all - the EExprs to accumulate.