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1 package kawa.lang;
2 import gnu.expr.*;
3 import gnu.mapping.*;
4 import gnu.lists.*;
5 import java.io.*;
6 import gnu.text.Printable;
7
8 public class Macro extends Syntax implements Printable, Externalizable
9 {
10 public Object  expander;
11
12 Object instance;
13
14 private boolean hygienic = true;
15
16 private ScopeExp capturedScope;
17
18 public ScopeExp getCapturedScope ()
19 {
20 if (capturedScope == null)
21 {
22 if (instance instanceof ModuleExp) capturedScope = (ModuleExp) instance;
24 else if (instance != null)
25 capturedScope = ModuleInfo.findFromInstance(instance).getModuleExp();
26 }
27 return capturedScope;
28 }
29
30 public void setCapturedScope (ScopeExp scope)
31 {
32 capturedScope = scope;
33 }
34
35 public static Macro make (Declaration decl)
36 {
37 Macro mac = new Macro(decl.getSymbol());
38 decl.setSyntax();
39 mac.capturedScope = decl.context;
40 return mac;
41 }
42
43 public static Macro makeNonHygienic (Object name, Procedure expander)
44 {
45 Macro mac = new Macro(name, expander);
46 mac.hygienic = false;
47 return mac;
48 }
49
50 public static Macro makeNonHygienic (Object name, Procedure expander,
51 Object instance)
52 {
53 Macro mac = new Macro(name, expander);
54 mac.hygienic = false;
55 mac.instance = instance;
56 return mac;
57 }
58
59 public static Macro make (Object name, Procedure expander)
60 {
61 Macro mac = new Macro(name, expander);
62 return mac;
63 }
64
65 public static Macro make(Object name, Procedure expander, Object instance)
66 {
67 Macro mac = new Macro(name, expander);
68 mac.instance = instance;
69 return mac;
70 }
71
72 public final boolean isHygienic() { return hygienic; }
73 public final void setHygienic (boolean hygienic) {this.hygienic = hygienic;}
74
75 public Macro ()
76 {
77 }
78
79
80 public Macro (Macro old)
81 {
82 name = old.name;
83 expander = old.expander;
84 hygienic = old.hygienic;
85 }
86
87 public Macro(Object name, Procedure expander)
88 {
89 super(name);
90 this.expander = new QuoteExp(expander);
91 }
92
93 public Macro(Object name)
94 {
95 super(name);
96 }
97
98
99 public gnu.expr.Expression rewriteForm (Pair form, Translator tr)
100 {
101 return tr.rewrite(expand(form, tr));
102 }
103
104 public gnu.expr.Expression rewriteForm (Object form, Translator tr)
105 {
106 return tr.rewrite(expand(form, tr));
107 }
108
109 public String toString()
110 {
111 return "#<macro "+getName()+'>';
112 }
113
114 public void print (Consumer out)
115 {
116 out.write("#<macro ");
117 out.write(getName());
118 out.write ('>');
119 }
120
121 public Object expand (Object form, Translator tr)
122 {
123 try
124 {
125 Procedure pr;
126 Object exp = expander;
127 if (exp instanceof Procedure && ! (exp instanceof Expression))
128 pr = (Procedure) exp;
129 else
130 {
131 if (! (exp instanceof Expression))
132 {
133 Macro savedMacro = tr.currentMacroDefinition;
134 tr.currentMacroDefinition = this;
135 try
136 {
137 exp = tr.rewrite(exp);
138 expander = exp;
139 }
140 finally
141 {
142 tr.currentMacroDefinition = savedMacro;
143 }
144 }
145
157 pr = (Procedure)
158 ((Expression) exp).eval(tr.getGlobalEnvironment());
159 }
160 Object result;
161 if (! hygienic)
162 {
163 form = Quote.quote(form, tr);
164 int nargs = Translator.listLength(form);
165 if (nargs <= 0)
166 return tr.syntaxError("invalid macro argument list to "+this);
167 Object [] args = new Object [nargs-1];
168 for (int i = 0; i < nargs; i++)
169 {
170 Pair pair = (Pair) form;
171 if (i > 0)
172 args[i-1] = pair.car;
173 form = pair.cdr;
174 }
175 result = pr.applyN(args);
176 }
177 else
178 result = pr.apply1(form);
179 if (form instanceof PairWithPosition && result instanceof Pair
180 && ! (result instanceof PairWithPosition))
181 {
182 Pair p = (Pair) result;
183 result = new PairWithPosition((PairWithPosition) form,
184 p.car, p.cdr);
185 }
186 return result;
187 }
188 catch (Throwable ex)
189 {
190 ex.printStackTrace();
191 return tr.syntaxError("evaluating syntax transformer '"
192 + getName() + "' threw " + ex);
193 }
194 }
195
196 public void scanForm (Pair st, ScopeExp defs, Translator tr)
197 {
198 String save_filename = tr.getFileName();
199 int save_line = tr.getLineNumber();
200 int save_column = tr.getColumnNumber();
201 Syntax saveSyntax = tr.currentSyntax;
202 try
203 {
204 tr.setLine(st);
205 tr.currentSyntax = this;
206 Object x = expand(st, tr);
207 tr.scanForm(x, defs);
208 }
209 finally
210 {
211 tr.setLine(save_filename, save_line, save_column);
212 tr.currentSyntax = saveSyntax;
213 }
214 }
215
216
220 public void writeExternal(ObjectOutput out) throws IOException
221 {
222 out.writeObject(getName());
223 out.writeObject(((QuoteExp) expander).getValue());
224 }
225
226 public void readExternal(ObjectInput in)
227 throws IOException, ClassNotFoundException
228 {
229 setName((String ) in.readObject());
230 expander = new QuoteExp(in.readObject());
231 }
232 }
233 |
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