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#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 parens(Datum, Datum);
Datum nameis(Datum, Datum);
Datum assign(Datum, Datum);
Datum monadop(Datum, Datum);
Datum dyadop(Datum, Datum);
Datum *lookup(Datum);
int bindingstrengths[13][13] = {
/* A F H MO DO AF ( ) [ ] ← IS N */
6, 3, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* A */
2, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* F */
0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* H */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* MO */
5, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* DO */
2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* AF */
0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, /* ( */
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, /* ) */
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, /* IS */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, /* N */
};
evalfn evalfns[13][13] = {
/* A F H MO DO AF ( ) [ ] ← IS N */
strand, dyadfun, 0, monadop, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* A */
monadfun, 0, 0, monadop, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* F */
0, 0, 0, monadop, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* H */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* MO */
dyadop, dyadop, dyadop, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* DO */
monadfun, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* AF */
0, 0, 0, 0, 0, 0, 0, parens, 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, /* IS */
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{
Datum new = fn(stmt->toks[offset],stmt->toks[offset+1]);
if(stmt->toks[offset].tag == ArrayTag)
freearray(stmt->toks[offset].array);
if(stmt->toks[offset+1].tag == ArrayTag)
freearray(stmt->toks[offset+1].array);
if(new.tag == ArrayTag){
Array *tmp = new.array;
new.array = simplifyarray(tmp);
freearray(tmp);
}
stmt->toks[offset] = new;
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;
}
Datum *val;
if(var.symbol->getfn != nil)
val = var.symbol->getfn();
else{
val = &var.symbol->value;
if(val->tag == ArrayTag)
incref(val->array); /* since the value is now in the var AND in the code */
}
val->shy = 0;
return val;
}
Datum
strand(Datum left, Datum right)
{
traceprint("Stranding (%d %d)\n", left.array->stranded, right.array->stranded);
Datum result;
result.shy = 0;
Array *leftarr = left.array->stranded ? fnSame(left.array) : fnEnclose(left.array);
Array *rightarr = right.array->stranded ? fnSame(right.array) : fnEnclose(right.array);
result.tag = ArrayTag;
result.array = fnCatenateFirst(leftarr, rightarr);
result.array->stranded = 1;
freearray(leftarr);
freearray(rightarr);
return result;
}
Datum
monadfun(Datum left, Datum right)
{
traceprint("Monadic function application\n");
Datum result;
result.tag = ArrayTag;
result.shy = 0;
result.array = runfunc(left.func, left.func.left, right.array);
return result;
}
Datum
dyadfun(Datum left, Datum right)
{
traceprint("Applying left argument to function\n");
Datum result;
result.shy = 0;
result.tag = BoundFunctionTag,
result.func = right.func;
result.func.left = left.array;
incref(left.array);
return result;
}
Datum
parens(Datum left, Datum right)
{
/* evaluate a parenthesis expression and return the result */
USED(right);
traceprint("PARENS: %S\n", ppdatums(left.stmt.toks, left.stmt.ntoks));
Datum *result = eval(&left.stmt);
if(result[0].tag == ArrayTag)
result[0].array->stranded = 0;
result[0].shy = 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)
{
if(left.symbol->setfn != nil){
int ok = left.symbol->setfn(right);
if(!ok){
print("Assignment failed\n");
exits(nil);
}
}else{
if(left.symbol->undefined == 0 && left.symbol->value.tag == ArrayTag)
freearray(left.symbol->value.array);
left.symbol->value = right;
left.symbol->undefined = 0;
if(left.symbol->value.tag == ArrayTag){
left.symbol->value.array->stranded = 0;
incref(right.array); /* for the binding */
}
}
right.shy = 1;
if(right.tag == ArrayTag)
incref(right.array); /* for the returned array */
return right;
}
Datum
monadop(Datum left, Datum right)
{
traceprint("Applying left argument to operator\n");
Datum *arg = emalloc(sizeof(Datum));
*arg = left;
Datum result;
result.shy = 0;
result.tag = FunctionTag,
result.func.type = FunctypeOp;
result.func.operator = right.operator;
result.func.operator.left = arg;
result.func.left = nil;
if(arg->tag == ArrayTag)
incref(arg->array);
return result;
}
Datum
dyadop(Datum left, Datum right)
{
traceprint("Applying right argument to operator\n");
Datum *arg = emalloc(sizeof(Datum));
*arg = right;
Datum result;
result.shy = 0;
result.tag = MonadicOpTag,
result.operator = left.operator;
result.operator.right = arg;
if(arg->tag == ArrayTag)
incref(arg->array);
return result;
}
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