Implement v1 in terms of v2 (#73)

Remove all the core functionality of v1 and instead implement it
in terms of v2 with the appropriate options specified.

Many v1 test cases currently fail because the v1 emulation in v2
insufficiently reproduces the historical v1 behavior.

The list of known failures are stored in v1/failing.txt,
which allows such failing tests to be skipped.

As the v1 emulation in v2 improves, the failing.txt list
should eventually become empty.

v1/bench_test.go

@@ -12,13 +12,8 @@ package json
 
 import (
 	"bytes"
-	"fmt"
 	"io"
-	"reflect"
-	"regexp"
-	"runtime"
 	"strings"
-	"sync"
 	"testing"
 
 	"github.com/go-json-experiment/json/internal/jsontest"
@@ -451,67 +446,6 @@ func BenchmarkUnmapped(b *testing.B) {
 	})
 }
 
-func BenchmarkTypeFieldsCache(b *testing.B) {
-	b.ReportAllocs()
-	var maxTypes int = 1e6
-
-	// Dynamically generate many new types.
-	types := make([]reflect.Type, maxTypes)
-	fs := []reflect.StructField{{
-		Type:  reflect.TypeFor[string](),
-		Index: []int{0},
-	}}
-	for i := range types {
-		fs[0].Name = fmt.Sprintf("TypeFieldsCache%d", i)
-		types[i] = reflect.StructOf(fs)
-	}
-
-	// clearClear clears the cache. Other JSON operations, must not be running.
-	clearCache := func() {
-		fieldCache = sync.Map{}
-	}
-
-	// MissTypes tests the performance of repeated cache misses.
-	// This measures the time to rebuild a cache of size nt.
-	for nt := 1; nt <= maxTypes; nt *= 10 {
-		ts := types[:nt]
-		b.Run(fmt.Sprintf("MissTypes%d", nt), func(b *testing.B) {
-			nc := runtime.GOMAXPROCS(0)
-			for i := 0; i < b.N; i++ {
-				clearCache()
-				var wg sync.WaitGroup
-				for j := 0; j < nc; j++ {
-					wg.Add(1)
-					go func(j int) {
-						for _, t := range ts[(j*len(ts))/nc : ((j+1)*len(ts))/nc] {
-							cachedTypeFields(t)
-						}
-						wg.Done()
-					}(j)
-				}
-				wg.Wait()
-			}
-		})
-	}
-
-	// HitTypes tests the performance of repeated cache hits.
-	// This measures the average time of each cache lookup.
-	for nt := 1; nt <= maxTypes; nt *= 10 {
-		// Pre-warm a cache of size nt.
-		clearCache()
-		for _, t := range types[:nt] {
-			cachedTypeFields(t)
-		}
-		b.Run(fmt.Sprintf("HitTypes%d", nt), func(b *testing.B) {
-			b.RunParallel(func(pb *testing.PB) {
-				for pb.Next() {
-					cachedTypeFields(types[0])
-				}
-			})
-		})
-	}
-}
-
 func BenchmarkEncodeMarshaler(b *testing.B) {
 	b.ReportAllocs()
 
@@ -545,29 +479,3 @@ func BenchmarkEncoderEncode(b *testing.B) {
 		}
 	})
 }
-
-func BenchmarkNumberIsValid(b *testing.B) {
-	s := "-61657.61667E+61673"
-	for i := 0; i < b.N; i++ {
-		isValidNumber(s)
-	}
-}
-
-func BenchmarkNumberIsValidRegexp(b *testing.B) {
-	var jsonNumberRegexp = regexp.MustCompile(`^-?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+-]?\d+)?$`)
-	s := "-61657.61667E+61673"
-	for i := 0; i < b.N; i++ {
-		jsonNumberRegexp.MatchString(s)
-	}
-}
-
-func BenchmarkUnmarshalNumber(b *testing.B) {
-	b.ReportAllocs()
-	data := []byte(`"-61657.61667E+61673"`)
-	var number Number
-	for i := 0; i < b.N; i++ {
-		if err := Unmarshal(data, &number); err != nil {
-			b.Fatal("Unmarshal:", err)
-		}
-	}
-}