From 7315b687249d4de8d0fb13fe8b0768ce0975ead4 Mon Sep 17 00:00:00 2001
From: NeilBrown <neil@brown.name>
Date: Sat, 18 Dec 2021 14:07:39 +1100
Subject: [PATCH] oceani: add a 'length' operator

array[] will now return the length of the array.

Signed-off-by: NeilBrown <neil@brown.name>
---
 csrc/oceani-tests.mdc |  8 ++++++--
 csrc/oceani.mdc       | 35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/csrc/oceani-tests.mdc b/csrc/oceani-tests.mdc
index 958575c..03aa850 100644
--- a/csrc/oceani-tests.mdc
+++ b/csrc/oceani-tests.mdc
@@ -322,7 +322,8 @@ Here I break it into two parts, keeping the array code separate.
 	func main(av:[ac::number]string)
 		A := $av[1]; B := $av[2]
 		astr := av[3]
-		bbool := av[ac-1] == "True"
+		l := av[]
+		bbool := av[l-1] == "True"
 		print "Hello World, what lovely oceans you have!"
 		/* When a variable is defined in both branches of an 'if',
 		 * and used afterwards, the variables are merged.
@@ -754,7 +755,7 @@ A simple linked list example
 
 		insert(list, "@start");
 		insert(list, "~end")
-		for i:=1; then i=i+1; while i < ac:
+		for i:=1; then i=i+1; while i < argv[]:
 			insert(list, argv[i])
 		insert(list, "Hello!")
 		printlist(list)
@@ -948,6 +949,7 @@ various places that `type_err()` are called.
 		while 1 if True else False:
 			print
 		case 2: print "two"
+		print "one" ++ a4[], c[]
 
 ###### output: type_err3
 	.tmp.code:8:12: error: expected number but variable 'c' is string
@@ -983,6 +985,8 @@ various places that `type_err()` are called.
 	.tmp.code:34:14: error: cannot find requested field in foo
 	.tmp.code:35:17: error: have string but need number
 	.tmp.code:38:29: error: expected number found Boolean
+	.tmp.code:41:23: error: have number but need string
+	.tmp.code:41:29: error: string cannot provide length
 	oceani: type error in program - not running.
 
 ###### test: type_err4
diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index 891ce74..fb154be 100644
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -2576,7 +2576,7 @@ with a const size by whether they are prepared at parse time or not.
 	} }$
 
 ###### Binode types
-	Index,
+	Index, Length,
 
 ###### term grammar
 
@@ -2588,6 +2588,13 @@ with a const size by whether they are prepared at parse time or not.
 		$0 = b;
 	} }$
 
+	| Term [ ] ${ {
+		struct binode *b = new(binode);
+		b->op = Length;
+		b->left = $<Term;
+		$0 = b;
+	} }$
+
 ###### print binode cases
 	case Index:
 		print_exec(b->left, -1, bracket);
@@ -2596,6 +2603,11 @@ with a const size by whether they are prepared at parse time or not.
 		printf("]");
 		break;
 
+	case Length:
+		print_exec(b->left, -1, bracket);
+		printf("[]");
+		break;
+
 ###### propagate binode cases
 	case Index:
 		/* left must be an array, right must be a number,
@@ -2615,6 +2627,20 @@ with a const size by whether they are prepared at parse time or not.
 		}
 		break;
 
+	case Length:
+		/* left must be an array, result is a number
+		 */
+		t = propagate_types(b->left, c, perr, NULL, 0);
+		if (!t || t->compat != array_compat) {
+			type_err(c, "error: %1 cannot provide length", prog, t, 0, NULL);
+			return NULL;
+		}
+		if (!type_compat(type, Tnum, rules))
+			type_err(c, "error: have %1 but need %2", prog,
+				         Tnum, rules, type);
+		return Tnum;
+		break;
+
 ###### interp binode cases
 	case Index: {
 		mpz_t q;
@@ -2640,6 +2666,13 @@ with a const size by whether they are prepared at parse time or not.
 		ltype = NULL;
 		break;
 	}
+	case Length: {
+		lleft = linterp_exec(c, b->left, &ltype);
+		mpq_set_ui(rv.num, ltype->array.size, 1);
+		ltype = NULL;
+		rvtype = Tnum;
+		break;
+	}
 
 #### Structs
 
-- 
2.43.0