1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
|
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "apl9.h"
#define traceprint if(traceeval)print
Rune *errormsg;
int traceeval;
typedef Datum (*evalfn)(Datum, Datum);
Datum strand(Datum, Datum);
Datum monadfun(Datum, Datum);
Datum dyadfun(Datum, Datum);
Datum lpar(Datum, Datum);
Datum rpar(Datum, Datum);
Datum nameis(Datum, Datum);
Datum assign(Datum, Datum);
Datum *lookup(Datum);
int bindingstrengths[15][15] = {
/* A F H MO DO AF ( ) { } [ ] ← IS N */
4, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* A */
2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* H */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* MO */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* DO */
2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* AF */
5, 5, 5, 5, 5, 5, 0, 6, 5, 5, 5, 5, 5, 5, 5, /* ( */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ) */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* { */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* } */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* [ */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ] */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ← */
1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* IS */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, /* N */
};
evalfn evalfns[15][15] = {
/* A F H MO DO AF ( ) { } [ ] ← IS N */
strand, dyadfun, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* A */
monadfun, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* H */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* MO */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* DO */
monadfun, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* AF */
lpar, lpar, lpar, lpar, lpar, 0, lpar, rpar, lpar, lpar, lpar, lpar, lpar, lpar, lpar, /* ( */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ) */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* { */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* } */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* [ */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ] */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ← */
assign, assign, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* IS */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, nameis, 0, 0, /* N */
};
Datum *
eval(Statement *stmt)
{
errormsg = nil;
/* start by looking up first variable if needed */
if(stmt->ntoks > 0 && stmt->toks[stmt->ntoks-1].tag == NameTag){
Datum *value = lookup(stmt->toks[stmt->ntoks-1]);
if(value == nil)
return nil;
else
stmt->toks[stmt->ntoks-1] = *value;
}
while(stmt->ntoks > 1){
int maxlevel = 0;
int offset;
evalfn fn = nil;
traceprint("CURRENT: %S\n", ppdatums(stmt->toks, stmt->ntoks));
for(offset = stmt->ntoks-1; offset >= 0; offset--){
int level;
retry:
if(offset == 0)
level = 0;
else{
Datum left = stmt->toks[offset-1];
Datum right = stmt->toks[offset];
level = bindingstrengths[left.tag][right.tag];
}
if(level == 0 && stmt->toks[offset-1].tag == NameTag){
Datum *value = lookup(stmt->toks[offset-1]);
if(value == nil)
return nil;
else{
stmt->toks[offset-1] = *value;
goto retry;
}
}else if(level < maxlevel){
Datum left = stmt->toks[offset];
Datum right = stmt->toks[offset+1];
fn = evalfns[left.tag][right.tag];
traceprint("Reducing %S and %S (fn=%p, level=%d, max=%d)\n", ppdatum(left), ppdatum(right), fn, level, maxlevel);
break;
}else if(level > maxlevel)
maxlevel = level;
}
if(maxlevel == 0){
errormsg = L"No reduce rule. Syntax error.";
return nil;
}else{
stmt->toks[offset] = fn(stmt->toks[offset],stmt->toks[offset+1]);
for(int i = offset+1; i < stmt->ntoks-1; i++)
stmt->toks[i] = stmt->toks[i+1];
stmt->ntoks--;
}
}
if(stmt->ntoks == 1){
if(stmt->next)
return eval(stmt->next);
else
return stmt->toks;
}else
return nil;
}
Datum *
lookup(Datum var)
{
traceprint("VAR LOOKUP %S\n", var.symbol->name);
if(var.symbol->undefined){
errormsg = runesmprint("Variable undefined: %S\n", var.symbol->name);
return nil;
}else
return &var.symbol->value;
}
Datum
strand(Datum left, Datum right)
{
traceprint("Stranding (%d %d)\n", left.array->stranded, right.array->stranded);
Datum result;
Array *leftarr = left.array->stranded ? left.array : fnEnclose(left.array);
Array *rightarr = right.array->stranded ? right.array : fnEnclose(right.array);
result.tag = ArrayTag;
result.array = fnCatenateFirst(leftarr, rightarr);
result.array->stranded = 1;
return result;
}
Datum
monadfun(Datum left, Datum right)
{
traceprint("Monadic function application\n");
Datum result;
result.tag = ArrayTag;
/* TODO handle undefined functions here */
if(left.func.left)
result.array = dyadfunctiondefs[left.func.code](left.func.left, right.array);
else
result.array = monadfunctiondefs[left.func.code](right.array);
return result;
}
Datum
dyadfun(Datum left, Datum right)
{
traceprint("Applying left argument to function\n");
Datum result;
result.tag = BoundFunctionTag,
result.func = right.func;
result.func.left = left.array;
return result;
}
Datum
lpar(Datum left, Datum right)
{
/* build up a parthenthesised expression */
left.stmt.ntoks++;
left.stmt.toks = realloc(left.stmt.toks, sizeof(Datum) * left.stmt.ntoks);
left.stmt.toks[left.stmt.ntoks-1] = right;
traceprint("LPAR: %S\n", ppdatums(left.stmt.toks, left.stmt.ntoks));
return left;
}
Datum
rpar(Datum left, Datum right)
{
/* evaluate a parenthesis expression and return the result */
USED(right);
traceprint("RPAR: %S\n", ppdatums(left.stmt.toks, left.stmt.ntoks));
Datum *result = eval(&left.stmt);
result[0].array->stranded = 0;
return result[0]; /* TODO handle error if ntoks != 1 */
}
Datum
nameis(Datum left, Datum right)
{
traceprint("NAME SYMBOL %p\n", left.symbol);
traceprint("NAMEIS %S←\n", left.symbol->name);
right.tag = AssignmentTag;
right.symbol = left.symbol;
return right;
}
Datum
assign(Datum left, Datum right)
{
left.symbol->value = right; /* TODO think about this*/
left.symbol->undefined = 0;
if(left.symbol->value.tag == ArrayTag)
left.symbol->value.array->stranded = 0;
right.shy = 1;
return right;
}
|