From 7c3dd2d1b7185ca12bfa149942187cfb8face4e1 Mon Sep 17 00:00:00 2001
From: Alex Gaynor <alex@alloy.us>
Date: Fri, 23 Aug 2019 16:35:36 -0400
Subject: [PATCH] Cache field encoders and setter

---
 decode.go | 4 ++--
 encode.go | 2 +-
 tags.go   | 4 ++++
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/decode.go b/decode.go
index d9e0d34..cd490b1 100644
--- a/decode.go
+++ b/decode.go
@@ -257,10 +257,10 @@ func structSetter(v reflect.Value, raw rawValue) error {
 		if !fieldSpec.ok {
 			continue
 		}
-		sf := t.Field(i)
 		rawValue := rawValueFromLine(raw, fieldSpec.startPos, fieldSpec.endPos)
-		err := newValueSetter(sf.Type)(v.Field(i), rawValue)
+		err := fieldSpec.setter(v.Field(i), rawValue)
 		if err != nil {
+			sf := t.Field(i)
 			return &UnmarshalTypeError{string(rawValue.bytes), sf.Type, t.Name(), sf.Name, err}
 		}
 	}
diff --git a/encode.go b/encode.go
index 64911f2..6f4902f 100644
--- a/encode.go
+++ b/encode.go
@@ -156,7 +156,7 @@ func structEncoder(v reflect.Value) ([]byte, error) {
 			continue
 		}
 
-		val, err := newValueEncoder(v.Field(i).Type())(v.Field(i))
+		val, err := spec.encoder(v.Field(i))
 		if err != nil {
 			return nil, err
 		}
diff --git a/tags.go b/tags.go
index 71a2a04..8377daf 100644
--- a/tags.go
+++ b/tags.go
@@ -37,6 +37,8 @@ type structSpec struct {
 
 type fieldSpec struct {
 	startPos, endPos int
+	encoder          valueEncoder
+	setter           valueSetter
 	ok               bool
 }
 
@@ -50,6 +52,8 @@ func buildStructSpec(t reflect.Type) structSpec {
 		if ss.fieldSpecs[i].endPos > ss.ll {
 			ss.ll = ss.fieldSpecs[i].endPos
 		}
+		ss.fieldSpecs[i].encoder = newValueEncoder(f.Type)
+		ss.fieldSpecs[i].setter = newValueSetter(f.Type)
 	}
 	return ss
 }