/* Alloy Analyzer 4 -- Copyright (c) 2006-2009, Felix Chang
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package edu.mit.csail.sdg.alloy4compiler.ast;
import java.util.Collection;
import java.util.List;
import edu.mit.csail.sdg.alloy4.ErrorType;
import edu.mit.csail.sdg.alloy4.Pos;
import edu.mit.csail.sdg.alloy4.Err;
import edu.mit.csail.sdg.alloy4.ErrorWarning;
import edu.mit.csail.sdg.alloy4.ErrorSyntax;
import edu.mit.csail.sdg.alloy4.JoinableList;
import edu.mit.csail.sdg.alloy4.Util;
/** Immutable; represents an expression of the form (let a=b | x).
*
* <p> <b>Invariant:</b> type!=EMPTY => (var.type.unambiguos() && sub.mult==0)
*/
public final class ExprLet extends Expr {
/** The LET variable. */
public final ExprVar var;
/** The expression bound to the LET variable. */
public final Expr expr;
/** The body of the LET expression. */
public final Expr sub;
/** Caches the span() result. */
private Pos span = null;
//=============================================================================================================//
/** {@inheritDoc} */
@Override public Pos span() {
Pos p = span;
if (p==null) span = (p = var.span().merge(expr.span()).merge(sub.span()));
return p;
}
//=============================================================================================================//
/** {@inheritDoc} */
@Override public void toString(StringBuilder out, int indent) {
if (indent<0) {
out.append("(let ").append(var.label).append("= ").append(expr.toString()).append(" | ");
sub.toString(out,-1);
out.append(')');
} else {
for(int i=0; i<indent; i++) { out.append(' '); }
out.append("let with type=").append(type).append('\n');
var.toString(out, indent+2);
expr.toString(out, indent+2);
sub.toString(out, indent+2);
}
}
//=============================================================================================================//
/** Constructs a LET expression. */
private ExprLet(Pos pos, ExprVar var, Expr expr, Expr sub, JoinableList<Err> errs) {
super(pos, null, expr.ambiguous || sub.ambiguous, sub.type, 0, var.weight + expr.weight + sub.weight, errs);
this.var = var;
this.expr = expr;
this.sub = sub;
}
//=============================================================================================================//
/** Constructs a LET expression.
*
* @param pos - the position of the '=' token in the original Alloy model (or null if unknown)
* @param var - the LET variable
* @param sub - the body of the LET expression (which may or may not contain "var" as a free variable)
*/
public static Expr make(Pos pos, ExprVar var, Expr expr, Expr sub) {
if (expr.ambiguous) expr = expr.resolve(expr.type, null);
JoinableList<Err> errs = var.errors.make(expr.errors).make(sub.errors);
if (expr.mult!=0)
errs = errs.make(new ErrorSyntax(expr.span(), "Multiplicity expression not allowed here."));
if (sub.mult != 0)
errs = errs.make(new ErrorSyntax(sub.span(), "Multiplicity expression not allowed here."));
if (errs.size()==0 && var.type!=expr.type)
if (/*[AM] var.type.is_int()!=expr.type.is_int()|| */
var.type.is_bool != expr.type.is_bool ||
var.type.arity() != expr.type.arity())
errs = errs.make(new ErrorType(var.span(), "This variable has type "+var.type+" but is bound to a value of type "+expr.type));
return new ExprLet(pos, var, expr, sub, errs);
}
//=============================================================================================================//
/** {@inheritDoc} */
@Override public Expr resolve(Type p, Collection<ErrorWarning> warns) {
if (errors.size()>0) return this;
// The var and expr are always already fully resolved, so we only need to resolve sub
Expr newSub = sub.resolve(p, warns);
if (warns!=null && !newSub.hasVar(var)) warns.add(new ErrorWarning(var.pos, "This variable is unused."));
return (sub==newSub) ? this : make(pos, var, expr, newSub);
}
//=============================================================================================================//
/** {@inheritDoc} */
public int getDepth() {
int a=var.getDepth(), b=sub.getDepth(), c=expr.getDepth();
if (a<b) a=b;
if (a<c) a=c;
return 1+a;
}
/** {@inheritDoc} */
@Override public final<T> T accept(VisitReturn<T> visitor) throws Err { return visitor.visit(this); }
/** {@inheritDoc} */
@Override public String getHTML() { return "<b>let</b> <i>" + type + "</i>"; }
/** {@inheritDoc} */
@Override public List<? extends Browsable> getSubnodes() {
Browsable a = make(var.pos, var.pos, "<b>var</b> "+var.label+" = ...", expr);
Browsable b = make(sub.span(), sub.span(), "<b>where...</b>", sub);
return Util.asList(a, b);
}
}