compiler,runtime: implement string to []rune conversion

Commit message by aykevl

compiler/compiler.go

@@ -2458,8 +2458,10 @@ func (c *Compiler) parseConvert(typeFrom, typeTo types.Type, value llvm.Value, p
 		switch elemType.Kind() {
 		case types.Byte:
 			return c.createRuntimeCall("stringToBytes", []llvm.Value{value}, ""), nil
+		case types.Rune:
+			return c.createRuntimeCall("stringToRunes", []llvm.Value{value}, ""), nil
 		default:
-			return llvm.Value{}, c.makeError(pos, "todo: convert from string: "+elemType.String())
+			panic("unexpected type in string to slice conversion")
 		}
 
 	default:

src/runtime/string.go

@@ -89,6 +89,21 @@ func stringToBytes(x _string) (slice struct {
 	return
 }
 
+// Convert a string to []rune slice.
+func stringToRunes(s string) []rune {
+	var n = 0
+	for range s {
+		n++
+	}
+	var r = make([]rune, n)
+	n = 0
+	for _, e := range s {
+		r[n] = e
+		n++
+	}
+	return r
+}
+
 // Create a string from a Unicode code point.
 func stringFromUnicode(x rune) _string {
 	array, length := encodeUTF8(x)

testdata/string.go

@@ -6,6 +6,14 @@ func testRangeString() {
 	}
 }
 
+func testStringToRunes() {
+	var s = "abcü¢€𐍈°x"
+	for i,c := range []rune(s) {
+		println(i, c)
+	}
+}
+
 func main() {
 	testRangeString()
+	testStringToRunes()
 }

testdata/string.txt

@@ -7,3 +7,12 @@
 10 66376
 14 176
 16 120
+0 97
+1 98
+2 99
+3 252
+4 162
+5 8364
+6 66376
+7 176
+8 120