Implement ( expr ) and improve stranding

1 files changed, 30 insertions, 3 deletions

diff --git a/eval.c b/eval.c
index da49137..1ee7033 100644
--- a/eval.c
+++ b/eval.c
@@ -10,6 +10,8 @@ typedef Datum (*evalfn)(Datum, Datum);
 
 Datum strand(Datum, Datum);
 Datum monadfun(Datum, Datum);
+Datum lpar(Datum, Datum);
+Datum rpar(Datum, Datum);
 
 int bindingstrengths[12][12] = {
 /*	A  F  H  MO DO AF (  )  {  }  [  ] */
@@ -19,7 +21,7 @@ int bindingstrengths[12][12] = {
 	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, /* DO */
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* FA */
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ( */
+	3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 3, 3, /* ( */
 	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, /* } */
@@ -35,7 +37,7 @@ evalfn evalfns[12][12] = {
 	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, /* DO */
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* FA */
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* ( */
+	lpar, lpar, lpar, lpar, lpar, lpar, lpar, rpar, 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, /* } */
@@ -88,8 +90,11 @@ strand(Datum left, Datum right)
 {
 	print("Stranding\n");
 	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(left.array,fnEnclose(right.array));
+	result.array = fnCatenateFirst(leftarr, rightarr);
+	result.array->stranded = 1;
 	return result;
 }
 
@@ -102,4 +107,26 @@ monadfun(Datum left, Datum right)
 	/* TODO handle undefined functions here */
 	result.array = monadfunctiondefs[left.code](right.array);
 	return result;
+}
+
+Datum
+lpar(Datum left, Datum right)
+{
+	/* build up a parthenthesised expression */
+	left.expr.ntoks++;
+	left.expr.toks = realloc(left.expr.toks, sizeof(Datum) * left.expr.ntoks);
+	left.expr.toks[left.expr.ntoks-1] = right;
+	print("LPAR: %S\n", ppdatums(left.expr.toks, left.expr.ntoks));
+	return left;
+}
+
+Datum
+rpar(Datum left, Datum right)
+{
+	/* evaluate a parenthesis expression and return the result */
+	USED(right);
+	print("RPAR: %S\n", ppdatums(left.expr.toks, left.expr.ntoks));
+	Datum *result = eval(left.expr.toks, &left.expr.ntoks);
+	result[0].array->stranded = 0;
+	return result[0]; /* TODO handle error if ntoks != 1 */
 }
\ No newline at end of file