docs(examples): add Num

README.md

@@ -128,6 +128,41 @@ fmt.Println(raw.Type(), raw)
 // array [1, 2, 3]
 ```
 
+## Number
+
+Use [jx.Decoder.Num](https://pkg.go.dev/github.com/ogen-go/jx#Decoder.Num) to read numbers, similar to `json.Number`.
+Also supports string numbers, like `"12345"`, which is common js-compatible way to represent `uint64`.
+
+```go
+d := jx.DecodeStr(`{"foo": "10531.0"}`)
+
+var n jx.Num
+if err := d.Obj(func(d *jx.Decoder, key string) error {
+    v, err := d.Num()
+    if err != nil {
+        return err
+    }
+    n = v
+    return nil
+}); err != nil {
+    panic(err)
+}
+
+fmt.Println(n)
+fmt.Println("positive:", n.Positive())
+
+// Can decode floats with zero fractional part as integers:
+v, err := n.Int64()
+if err != nil {
+    panic(err)
+}
+fmt.Println("int64:", v)
+// Output:
+// "10531.0"
+// positive: true
+// int64: 10531
+```
+
 ## Validate
 
 Check that byte slice is valid json with [jx.Valid](https://pkg.go.dev/github.com/ogen-go/jx#Valid):

examples_test.go

@@ -106,3 +106,34 @@ func ExampleDecoder_Raw() {
 	// Output:
 	// array [1, 2, 3]
 }
+
+func ExampleDecoder_Num() {
+	// Can decode numbers and number strings.
+	d := jx.DecodeStr(`{"foo": "10531.0"}`)
+
+	var n jx.Num
+	if err := d.Obj(func(d *jx.Decoder, key string) error {
+		v, err := d.Num()
+		if err != nil {
+			return err
+		}
+		n = v
+		return nil
+	}); err != nil {
+		panic(err)
+	}
+
+	fmt.Println(n)
+	fmt.Println("positive:", n.Positive())
+
+	// Can decode floats with zero fractional part as integers:
+	v, err := n.Int64()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println("int64:", v)
+	// Output:
+	// "10531.0"
+	// positive: true
+	// int64: 10531
+}

num.go

@@ -12,9 +12,14 @@ import (
 type Num []byte
 
 func (n Num) dec() Decoder {
+	head := 0
+	if n.Str() {
+		head = 1
+	}
 	return Decoder{
 		buf:  n,
 		tail: len(n),
+		head: head,
 	}
 }
 
@@ -34,7 +39,9 @@ func (n Num) floatAsInt() error {
 		if !dot {
 			continue
 		}
-		if c != '0' {
+		switch c {
+		case '0', '"': // ok
+		default:
 			return errors.Wrap(badToken(c), "non-zero fractional part")
 		}
 	}