wip-devtools

json_tree.go

@@ -0,0 +1,93 @@
+package mujica
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"regexp"
+	"strconv"
+)
+
+// jsonNode is one value of a parsed document, in document order.
+type jsonNode struct {
+	key, path string
+	// value is a scalar's JSON text, or "{}" / "[]" for containers.
+	value  string
+	depth  int
+	parent int
+	// end is the index after this node's subtree; count is its child count.
+	end, count int
+}
+
+func (n jsonNode) container() bool { return n.value == "{}" || n.value == "[]" }
+
+func (n jsonNode) label() string {
+	if n.key == "" {
+		return n.value
+	}
+	return n.key + ": " + n.value
+}
+
+// jsonTree is a document flattened depth-first.
+type jsonTree struct{ nodes []jsonNode }
+
+var jsonIdent = regexp.MustCompile(`^[A-Za-z_$][A-Za-z0-9_$]*$`)
+
+// parseJSONTree flattens data keeping key order; it fails on invalid or trailing JSON.
+func parseJSONTree(data string) (jsonTree, error) {
+	dec := json.NewDecoder(bytes.NewReader([]byte(data)))
+	dec.UseNumber()
+	var t jsonTree
+	if err := jsonParseValue(dec, &t, "", "$", 0, -1); err != nil {
+		return jsonTree{}, err
+	}
+	if _, err := dec.Token(); err != io.EOF {
+		return jsonTree{}, fmt.Errorf("unexpected data after the value")
+	}
+	return t, nil
+}
+
+func jsonParseValue(dec *json.Decoder, t *jsonTree, key, path string, depth, parent int) error {
+	tok, err := dec.Token()
+	if err != nil {
+		return err
+	}
+	at := len(t.nodes)
+	t.nodes = append(t.nodes, jsonNode{key: key, path: path, depth: depth, parent: parent})
+	switch v := tok.(type) {
+	case json.Delim:
+		t.nodes[at].value = map[json.Delim]string{'{': "{}", '[': "[]"}[v]
+		for i := 0; dec.More(); i++ {
+			childKey, childPath := "", fmt.Sprintf("%s[%d]", path, i)
+			if v == '{' {
+				kt, err := dec.Token()
+				if err != nil {
+					return err
+				}
+				childKey = kt.(string)
+				childPath = path + "." + childKey
+				if !jsonIdent.MatchString(childKey) {
+					childPath = path + "[" + strconv.Quote(childKey) + "]"
+				}
+			}
+			if err := jsonParseValue(dec, t, childKey, childPath, depth+1, at); err != nil {
+				return err
+			}
+			t.nodes[at].count++
+		}
+		if _, err := dec.Token(); err != nil { // the closing delimiter
+			return err
+		}
+	case string:
+		t.nodes[at].value = strconv.Quote(v)
+	case json.Number:
+		t.nodes[at].value = v.String()
+	case bool:
+		t.nodes[at].value = strconv.FormatBool(v)
+	case nil:
+		t.nodes[at].value = "null"
+	}
+	t.nodes[at].end = len(t.nodes)
+	return nil
+}