encoding/json: streamline, unexport valid Number checking

Followup to CL 12250.

For #10281.

Change-Id: If25d9cac92f10327bb355f2d11b00c625b464661
Reviewed-on: https://go-review.googlesource.com/17199
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/encoding/json/decode.go b/src/encoding/json/decode.go
index 6dc1b9d5b63c32934e4216a2f5be16a21a5b6051..099d7f6da53847632d32de9ebadcad50d8244edc 100644 (file)
--- a/src/encoding/json/decode.go
+++ b/src/encoding/json/decode.go
@@ -60,7 +60,7 @@ import (
 // If the JSON array is smaller than the Go array,
 // the additional Go array elements are set to zero values.
 //
-// To unmarshal a JSON object into a string-keyed map, Unmarshal first 
+// To unmarshal a JSON object into a string-keyed map, Unmarshal first
 // establishes a map to use, If the map is nil, Unmarshal allocates a new map.
 // Otherwise Unmarshal reuses the existing map, keeping existing entries.
 // Unmarshal then stores key-value pairs from the JSON object into the map.
@@ -184,122 +184,64 @@ func (n Number) Int64() (int64, error) {
        return strconv.ParseInt(string(n), 10, 64)
 }
 
-// IsValid returns if the number is a valid JSON number literal.
-func (n Number) IsValid() bool {
+// isValidNumber reports whether s is a valid JSON number literal.
+func isValidNumber(s string) bool {
        // This function implements the JSON numbers grammar.
        // See https://tools.ietf.org/html/rfc7159#section-6
        // and http://json.org/number.gif
 
-       l := len(n)
-       if l == 0 {
+       if s == "" {
                return false
        }
 
-       i := 0
-       c := n[i]
-       i++
-
        // Optional -
-       if c == '-' {
-               if i == l {
+       if s[0] == '-' {
+               s = s[1:]
+               if s == "" {
                        return false
                }
-
-               c = n[i]
-               i++
        }
 
-       // 1-9
-       if c >= '1' && c <= '9' {
-               // Eat digits.
-               for ; i < l; i++ {
-                       c = n[i]
-                       if c < '0' || c > '9' {
-                               break
-                       }
-               }
-               i++
-       } else if c != '0' {
-               // If it's not 0 or 1-9 it's invalid.
+       // Digits
+       switch {
+       default:
                return false
-       } else {
-               if i == l {
-                       // Just 0
-                       return true
-               }
 
-               // Skip the 0
-               c = n[i]
-               i++
-       }
-
-       // . followed by 1 or more digits.
-       if c == '.' {
-               if i == l {
-                       // Just 1. is invalid.
-                       return false
-               }
+       case s[0] == '0':
+               s = s[1:]
 
-               // . needs to be followed by at least one digit.
-               c = n[i]
-               i++
-               if c < '0' || c > '9' {
-                       return false
+       case '1' <= s[0] && s[0] <= '9':
+               s = s[1:]
+               for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+                       s = s[1:]
                }
+       }
 
-               // Eat digits.
-               for ; i < l; i++ {
-                       c = n[i]
-                       if c < '0' || c > '9' {
-                               break
-                       }
+       // . followed by 1 or more digits.
+       if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' {
+               s = s[2:]
+               for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+                       s = s[1:]
                }
-               i++
        }
 
        // e or E followed by an optional - or + and
        // 1 or more digits.
-       if c == 'e' || c == 'E' {
-               if i == l {
-                       // Just 1e is invalid.
-                       return false
-               }
-
-               c = n[i]
-               i++
-
-               // Optional - or +
-               if c == '-' || c == '+' {
-                       if i == l {
-                               // Just 1e+ is invalid.
+       if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
+               s = s[1:]
+               if s[0] == '+' || s[0] == '-' {
+                       s = s[1:]
+                       if s == "" {
                                return false
                        }
-
-                       c = n[i]
-                       i++
                }
-
-               // Need to have a digit.
-               if c < '0' || c > '9' {
-                       return false
-               }
-
-               // Eat digits.
-               for ; i < l; i++ {
-                       c = n[i]
-                       if c < '0' || c > '9' {
-                               break
-                       }
+               for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
+                       s = s[1:]
                }
-               i++
        }
 
        // Make sure we are at the end.
-       if i <= l {
-               return false
-       }
-
-       return true
+       return s == ""
 }
 
 // decodeState represents the state while decoding a JSON value.
@@ -909,7 +851,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
                default:
                        if v.Kind() == reflect.String && v.Type() == numberType {
                                v.SetString(s)
-                               if !Number(s).IsValid() {
+                               if !isValidNumber(s) {
                                        d.error(fmt.Errorf("json: invalid number literal, trying to unmarshal %q into Number", item))
                                }
                                break

diff --git a/src/encoding/json/encode.go b/src/encoding/json/encode.go
index 364e2724b7afb1fe198f1bdea0482b739c195bf8..69ac7e03c8db81c2ebcc5d14765e6b5a3a441215 100644 (file)
--- a/src/encoding/json/encode.go
+++ b/src/encoding/json/encode.go
@@ -534,8 +534,9 @@ func stringEncoder(e *encodeState, v reflect.Value, quoted bool) {
                // we keep compatibility so check validity after this.
                if numStr == "" {
                        numStr = "0" // Number's zero-val
-               } else if !Number(numStr).IsValid() {
-                       e.error(fmt.Errorf("json: invalid number literal, trying to marshal %s", v.String()))
+               }
+               if !isValidNumber(numStr) {
+                       e.error(fmt.Errorf("json: invalid number literal %q", numStr))
                }
                e.WriteString(numStr)
                return

diff --git a/src/encoding/json/number_test.go b/src/encoding/json/number_test.go
index 702d4ea58d1a6547c6083d6754153b94a73c7573..4e63cf9c74e81a89c1120efb5a12e8813119752b 100644 (file)
--- a/src/encoding/json/number_test.go
+++ b/src/encoding/json/number_test.go
@@ -63,17 +63,17 @@ func TestNumberIsValid(t *testing.T) {
        }
 
        for _, test := range validTests {
-               if !Number(test).IsValid() {
+               if !isValidNumber(test) {
                        t.Errorf("%s should be valid", test)
                }
 
                var f float64
                if err := Unmarshal([]byte(test), &f); err != nil {
-                       t.Errorf("%s should be invalid: %v", test, err)
+                       t.Errorf("%s should be valid but Unmarshal failed: %v", test, err)
                }
 
                if !jsonNumberRegexp.MatchString(test) {
-                       t.Errorf("%s should be invalid", test)
+                       t.Errorf("%s should be valid but regexp does not match", test)
                }
        }
 
@@ -102,32 +102,32 @@ func TestNumberIsValid(t *testing.T) {
        }
 
        for _, test := range invalidTests {
-               if Number(test).IsValid() {
+               if isValidNumber(test) {
                        t.Errorf("%s should be invalid", test)
                }
 
                var f float64
                if err := Unmarshal([]byte(test), &f); err == nil {
-                       t.Errorf("%s should be valid: %v", test, f)
+                       t.Errorf("%s should be invalid but unmarshal wrote %v", test, f)
                }
 
                if jsonNumberRegexp.MatchString(test) {
-                       t.Errorf("%s should be valid", test)
+                       t.Errorf("%s should be invalid but matches regexp", test)
                }
        }
 }
 
 func BenchmarkNumberIsValid(b *testing.B) {
-       n := Number("-61657.61667E+61673")
+       s := "-61657.61667E+61673"
        for i := 0; i < b.N; i++ {
-               n.IsValid()
+               isValidNumber(s)
        }
 }
 
 func BenchmarkNumberIsValidRegexp(b *testing.B) {
        var jsonNumberRegexp = regexp.MustCompile(`^-?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+-]?\d+)?$`)
-       n := "-61657.61667E+61673"
+       s := "-61657.61667E+61673"
        for i := 0; i < b.N; i++ {
-               jsonNumberRegexp.MatchString(n)
+               jsonNumberRegexp.MatchString(s)
        }
 }