feat:(ast) Visitor support skip object and array

ast/parser.go

@@ -115,6 +115,10 @@ func (self *Parser) lspace(sp int) int {
     return sp
 }
 
+func (self *Parser) backward() {
+    for ; self.p >= 0 && isSpace(self.s[self.p]); self.p-=1 {}
+}
+
 func (self *Parser) decodeArray(ret *linkedNodes) (Node, types.ParsingError) {
     sp := self.p
     ns := len(self.s)

ast/visitor.go

@@ -18,6 +18,7 @@ package ast
 
 import (
     `encoding/json`
+    `errors`
 
     `github.com/bytedance/sonic/internal/native/types`
 )
@@ -174,6 +175,19 @@ func (self *traverser) decodeArray() error {
     sp := self.parser.p
     ns := len(self.parser.s)
 
+    /* allocate array space and parse every element */
+    if err := self.visitor.OnArrayBegin(_DEFAULT_NODE_CAP); err != nil {
+        if err == VisitOPSkip {
+            // NOTICE: for user needs to skip entiry object
+            self.parser.p -= 1
+            if _, e := self.parser.skipFast(); e != 0 {
+                return e
+            }
+            return self.visitor.OnArrayEnd()
+        }
+        return err
+    }
+
     /* check for EOF */
     self.parser.p = self.parser.lspace(sp)
     if self.parser.p >= ns {
@@ -183,16 +197,9 @@ func (self *traverser) decodeArray() error {
     /* check for empty array */
     if self.parser.s[self.parser.p] == ']' {
         self.parser.p++
-        if err := self.visitor.OnArrayBegin(0); err != nil {
-            return err
-        }
         return self.visitor.OnArrayEnd()
     }
 
-    /* allocate array space and parse every element */
-    if err := self.visitor.OnArrayBegin(_DEFAULT_NODE_CAP); err != nil {
-        return err
-    }
     for {
         /* decode the value */
         if err := self.decodeValue(); err != nil {
@@ -223,6 +230,19 @@ func (self *traverser) decodeObject() error {
     sp := self.parser.p
     ns := len(self.parser.s)
 
+    /* allocate object space and decode each pair */
+    if err := self.visitor.OnObjectBegin(_DEFAULT_NODE_CAP); err != nil {
+        if err == VisitOPSkip {
+            // NOTICE: for user needs to skip entiry object
+            self.parser.p -= 1
+            if _, e := self.parser.skipFast(); e != 0 {
+                return e
+            }
+            return self.visitor.OnObjectEnd()
+        }
+        return err
+    }
+
     /* check for EOF */
     self.parser.p = self.parser.lspace(sp)
     if self.parser.p >= ns {
@@ -231,17 +251,9 @@ func (self *traverser) decodeObject() error {
 
     /* check for empty object */
     if self.parser.s[self.parser.p] == '}' {
-        self.parser.p++
-        if err := self.visitor.OnObjectBegin(0); err != nil {
-            return err
-        }
         return self.visitor.OnObjectEnd()
     }
 
-    /* allocate object space and decode each pair */
-    if err := self.visitor.OnObjectBegin(_DEFAULT_NODE_CAP); err != nil {
-        return err
-    }
     for {
         var njs types.JsonState
         var err types.ParsingError
@@ -313,3 +325,7 @@ func (self *traverser) decodeString(iv int64, ep int) error {
     }
     return self.visitor.OnString(out)
 }
+
+// If visitor return this error on `OnObjectBegin()` or `OnArrayBegin()`, 
+// the transverer will skip entiry object or array
+var VisitOPSkip = errors.New("")

ast/visitor_test.go

@@ -648,6 +648,115 @@ func TestVisitor_UserNodeDiff(t *testing.T) {
     })
 }
 
+type skipVisitor struct {
+    sp int
+    Skip int
+    inSkip bool
+    CountSkip int
+}
+
+func (self *skipVisitor) OnNull() error {
+    if self.sp == self.Skip+1 && self.inSkip  {
+        panic("unexpected key")
+    }
+    return nil
+}
+
+func (self *skipVisitor) OnFloat64(v float64, n json.Number) error {
+    if self.sp == self.Skip+1 && self.inSkip  {
+        panic("unexpected key")
+    }
+    return nil
+}
+
+func (self *skipVisitor) OnInt64(v int64, n json.Number) error {
+    if self.sp == self.Skip+1 && self.inSkip  {
+        panic("unexpected key")
+    }
+    return nil
+}
+
+func (self *skipVisitor) OnBool(v bool) error {
+    if self.sp == self.Skip+1 && self.inSkip  {
+        panic("unexpected key")
+    }
+    return nil
+}
+
+func (self *skipVisitor) OnString(v string) error {
+    if self.sp == self.Skip+1 && self.inSkip  {
+        panic("unexpected key")
+    }
+    return nil
+}
+
+func (self *skipVisitor) OnObjectBegin(capacity int) error {
+    println("self.sp", self.sp)
+    if self.sp == self.Skip {
+        self.inSkip = true
+        self.CountSkip++
+        println("op skip")
+        self.sp++
+        return VisitOPSkip
+    }
+    self.sp++
+    return nil
+}
+
+func (self *skipVisitor) OnObjectKey(key string) error {
+    if self.sp == self.Skip+1 && self.inSkip  {
+        panic("unexpected key")
+    }
+    return nil
+}
+
+func (self *skipVisitor) OnObjectEnd() error {
+    if self.sp == self.Skip + 1 {
+        if !self.inSkip {
+            panic("not in skip")
+        }
+        self.inSkip = false
+        println("finish op skip")
+    }
+    self.sp--
+    return nil
+}
+
+func (self *skipVisitor) OnArrayBegin(capacity int) error {
+    println("arr self.sp", self.sp)
+    if self.sp == self.Skip {
+        self.inSkip = true
+        self.CountSkip++
+        println("arr op skip")
+        self.sp++
+        return VisitOPSkip
+    }
+    self.sp++
+    return nil
+}
+
+func (self *skipVisitor) OnArrayEnd() error {
+    println("arr self.sp", self.sp)
+    if self.sp == self.Skip + 1 {
+        if !self.inSkip {
+            panic("arr not in skip")
+        }
+        self.inSkip = false
+        println("arr finish op skip")
+    }
+    self.sp--
+    return nil
+}
+
+func TestVisitor_OpSkip(t *testing.T) {
+    var suite skipVisitor
+    suite.Skip = 1
+    Preorder(`{ "a": [ null ] , "b": 1, "c": { "1" : 1 } }`, &suite, nil)
+    if suite.CountSkip != 2 {
+        t.Fatal(suite.CountSkip)
+    }
+}
+
 func BenchmarkVisitor_UserNode(b *testing.B) {
     const str = _TwitterJson
     b.Run("AST", func(b *testing.B) {