runtime: map

ssa/datastruct.go

@@ -365,3 +365,50 @@ func (b Builder) MapUpdate(m, k, v Expr) {
 }
 
 // -----------------------------------------------------------------------------
+
+// The Range instruction yields an iterator over the domain and range
+// of X, which must be a string or map.
+//
+// Elements are accessed via Next.
+//
+// Type() returns an opaque and degenerate "rangeIter" type.
+//
+// Pos() returns the ast.RangeStmt.For.
+//
+// Example printed form:
+//
+//	t0 = range "hello":string
+func (b Builder) Range(x Expr) Expr {
+	switch x.kind {
+	case vkString:
+		return b.InlineCall(b.Pkg.rtFunc("NewStringIter"), x)
+	}
+	panic("todo")
+}
+
+// The Next instruction reads and advances the (map or string)
+// iterator Iter and returns a 3-tuple value (ok, k, v).  If the
+// iterator is not exhausted, ok is true and k and v are the next
+// elements of the domain and range, respectively.  Otherwise ok is
+// false and k and v are undefined.
+//
+// Components of the tuple are accessed using Extract.
+//
+// The IsString field distinguishes iterators over strings from those
+// over maps, as the Type() alone is insufficient: consider
+// map[int]rune.
+//
+// Type() returns a *types.Tuple for the triple (ok, k, v).
+// The types of k and/or v may be types.Invalid.
+//
+// Example printed form:
+//
+//	t1 = next t0
+func (b Builder) Next(iter Expr, isString bool) (ret Expr) {
+	if isString {
+		return b.InlineCall(b.Pkg.rtFunc("StringIterNext"), iter)
+	}
+	panic("todo")
+}
+
+// -----------------------------------------------------------------------------