Moved AST generation to its own package

src/build/ast/EachInstruction.go

@@ -0,0 +1,46 @@
+package ast
+
+import "git.akyoto.dev/cli/q/src/build/token"
+
+// EachInstruction calls the function on each instruction.
+func EachInstruction(body token.List, call func(token.List) error) error {
+	start := 0
+	groupLevel := 0
+	blockLevel := 0
+
+	for i, t := range body {
+		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(body[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--
+		}
+	}
+
+	return nil
+}