chore: remove files for old Go versions

Author: jszwec

.github/workflows/go.yml

@@ -11,7 +11,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.17, 1.18]
+        go-version: ["1.20"]
         os: [ubuntu-latest, macos-latest, windows-latest]
 
     runs-on: ${{ matrix.os }}
@@ -35,7 +35,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [1.8, 1.9, "1.10"]
+        go-version: [1.18, 1.19]
     steps:
     - uses: actions/checkout@v2
       with:

cache.go

@@ -3,8 +3,20 @@ package csvutil
 import (
 	"reflect"
 	"sort"
+	"sync"
 )
 
+var fieldCache sync.Map // map[typeKey][]field
+
+func cachedFields(k typeKey) fields {
+	if v, ok := fieldCache.Load(k); ok {
+		return v.(fields)
+	}
+
+	v, _ := fieldCache.LoadOrStore(k, buildFields(k))
+	return v.(fields)
+}
+
 type field struct {
 	name     string
 	baseType reflect.Type

cache_go17.go

@@ -221,3 +221,9 @@ loop:
 	}
 	return typ, nil
 }
+
+func newCSVReader(r io.Reader) *csv.Reader {
+	rr := csv.NewReader(r)
+	rr.ReuseRecord = true
+	return rr
+}