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1
4 package gnu.expr;
5 import gnu.bytecode.*;
6 import gnu.mapping.*;
7
8
12
13 public class ReferenceExp extends AccessExp
14 {
15 static int counter;
16
17 int id = ++counter;
18
19 public static final int DONT_DEREFERENCE = NEXT_AVAIL_FLAG;
20 public static final int PROCEDURE_NAME = NEXT_AVAIL_FLAG << 1;
21 public static final int PREFER_BINDING2 = NEXT_AVAIL_FLAG << 2;
22
23 public static final int CREATE_FIELD_REFERENCE = NEXT_AVAIL_FLAG << 3;
24
25
26 public final boolean getDontDereference()
27 {
28 return (flags & DONT_DEREFERENCE) != 0;
29 }
30
31 public final void setDontDereference(boolean setting)
32 { setFlag(setting, DONT_DEREFERENCE); }
33
34 public final boolean isUnknown ()
35 {
36 return Declaration.isUnknown(binding);
37 }
38
39
42 public final boolean isProcedureName()
43 {
44 return (flags & PROCEDURE_NAME) != 0;
45 }
46
47
48 public final void setProcedureName(boolean setting)
49 {
50 setFlag(setting, PROCEDURE_NAME);
51 }
52
53 public ReferenceExp (Object  symbol)
54 {
55 this.symbol = symbol;
56 }
57
58 public ReferenceExp (Object symbol, Declaration binding)
59 {
60 this.symbol = symbol;
61 this.binding = binding;
62 }
63
64 public ReferenceExp (Declaration binding)
65 {
66 this(binding.getSymbol(), binding);
67 }
68
69 protected boolean mustCompile () { return false; }
70
71 public void apply (CallContext ctx)
72 throws Throwable
73 {
74 Object value;
75 if (binding != null && binding.isAlias() && ! getDontDereference()
76 && binding.value instanceof ReferenceExp)
77 {
78 ReferenceExp rexp = (ReferenceExp) binding.value;
79 if (rexp.getDontDereference() && rexp.binding != null)
80 {
81 Expression v = rexp.binding.getValue();
82 if (v instanceof QuoteExp || v instanceof ReferenceExp
83 || v instanceof LambdaExp)
84 {
85 v.apply(ctx);
86 return;
87 }
88 }
89 value = binding.value.eval(ctx);
90 }
91 else if (binding != null && binding.field != null
92 && binding.field.getDeclaringClass().isExisting()
93 && (! getDontDereference() || binding.isIndirectBinding()))
94 {
95 try
96 {
97 Object instance = binding.field.getStaticFlag() ? null
98 : contextDecl().getValue().eval(ctx);
99 value = binding.field.getReflectField().get(instance);
100 }
101 catch (Exception ex)
102 {
103 String msg = "exception evaluating "+symbol
104 +" from "+binding.field+" - "+ex;
105 throw new UnboundLocationException(msg, this);
107 }
108 }
109 else if (binding != null
112 && (binding.value instanceof QuoteExp
113 || binding.value instanceof LambdaExp)
114 && binding.value != QuoteExp.undefined_exp
115 && (! getDontDereference() || binding.isIndirectBinding()))
116 {
117 value = binding.value.eval(ctx);
118 }
119 else if (binding == null
120 || (binding.context instanceof ModuleExp
121 && ! binding.isPrivate()))
122 {
123 Environment env = ctx.getEnvironment();
124 Symbol sym = symbol instanceof Symbol ? (Symbol) symbol
125 : env.getSymbol(symbol.toString());
126 Object property = getFlag(PREFER_BINDING2) && isProcedureName()
127 ? EnvironmentKey.FUNCTION
128 : null;
129 if (getDontDereference())
130 value = env.getLocation(sym, property);
131 else
132 {
133 Object unb = gnu.mapping.Location.UNBOUND;
134 value = env.get(sym, property, unb);
135 if (value == unb)
136 throw new UnboundLocationException(sym, this);
137 }
138 ctx.writeValue(value);
139 return;
140 }
141 else
142 value = ctx.evalFrames[ScopeExp.nesting(binding.context)][binding.evalIndex];
143 if (! getDontDereference() && binding.isIndirectBinding())
144 value = ((gnu.mapping.Location) value).get();
145 ctx.writeValue(value);
146 }
147
148 public void compile (Compilation comp, Target target)
149 {
150 if (! (target instanceof ConsumerTarget)
151 || ! ((ConsumerTarget) target).compileWrite(this, comp))
152 binding.load(this, flags, comp, target);
153 }
154
155 protected Expression walk (ExpWalker walker)
156 {
157 return walker.walkReferenceExp(this);
158 }
159 public Expression inline (ApplyExp exp, InlineCalls walker, Declaration decl)
160 {
161 decl = this.binding; if (decl != null && ! decl.getFlag(Declaration.IS_UNKNOWN))
163 {
164 decl = Declaration.followAliases(decl);
165 if (decl.isIndirectBinding())
166 return exp;
167 Expression dval = decl.getValue();
168 if (dval != null)
169 return dval.inline(exp, walker, decl);
170 }
171 else if (getSymbol() instanceof Symbol)
172 {
173 Symbol symbol = (Symbol) getSymbol();
174 Object fval = Environment.getCurrent().getFunction(symbol, null);
175 if (fval instanceof Procedure)
176 return new QuoteExp(fval).inline(exp, walker, null);
177 }
178 return exp;
179 }
180
181 public void print (OutPort ps)
182 {
183 ps.print("(Ref/");
184 ps.print(id);
185 if (symbol != null
186 && (binding == null || symbol.toString() != binding.getName()))
187 {
188 ps.print('/');
189 ps.print(symbol);
190 }
191 if (binding != null)
192 {
193 ps.print('/');
194 ps.print(binding);
195 }
196 ps.print(")");
197 }
198
199 public gnu.bytecode.Type getType()
200 {
201 Declaration decl = binding;
202 if (decl == null || decl.isFluid())
203 return Type.pointer_type;
204 if (getDontDereference())
205 return Compilation.typeLocation;
206 decl = Declaration.followAliases(decl);
207 Type type = decl.getType();
208 if (type == null || type == Type.pointer_type)
209 {
210 Expression value = decl.getValue();
211 if (value != null)
212 {
213 Expression save = decl.value;
216 decl.value = null;
217 type = value.getType();
218 decl.value = save;
219 }
220 }
221 return type;
222 }
223
224 public boolean side_effects ()
225 {
226 return binding == null || ! binding.isLexical();
227 }
228
229 public String toString()
230 {
231 return "RefExp/"+symbol+'/'+id+'/';
232 }
233 }
234 |
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