Simplified ast package

src/ast/eachInstruction.go

@@ -0,0 +1,62 @@
+package ast
+
+import "git.akyoto.dev/cli/q/src/token"
+
+// eachInstruction calls the function on each AST node.
+func eachInstruction(tokens token.List, call func(token.List) error) error {
+	start := 0
+	groupLevel := 0
+	blockLevel := 0
+
+	for i, t := range tokens {
+		if start == i && t.Kind == token.NewLine {
+			start = i + 1
+			continue
+		}
+
+		switch t.Kind {
+		case token.NewLine:
+			if groupLevel > 0 || blockLevel > 0 {
+				continue
+			}
+
+			err := call(tokens[start:i])
+
+			if err != nil {
+				return err
+			}
+
+			start = i + 1
+
+		case token.GroupStart:
+			groupLevel++
+
+		case token.GroupEnd:
+			groupLevel--
+
+		case token.BlockStart:
+			blockLevel++
+
+		case token.BlockEnd:
+			blockLevel--
+
+			if groupLevel > 0 || blockLevel > 0 {
+				continue
+			}
+
+			err := call(tokens[start : i+1])
+
+			if err != nil {
+				return err
+			}
+
+			start = i + 1
+		}
+	}
+
+	if start != len(tokens) {
+		return call(tokens[start:])
+	}
+
+	return nil
+}