From 9239d9c4b4a6b1eb0cdc7a00f75b88d01a7202b1 Mon Sep 17 00:00:00 2001
From: Gian Lorenzo Meocci <glmeocci@gmail.com>
Date: Sun, 27 Oct 2019 16:37:36 +0100
Subject: [PATCH] add UseColums function to avoid extra allocation performed by
 Colums function

fix name

tidy

adding SetWhere

adding SetWhere

fix go mod

fix comment style

revert go mod

Avoid to append if no needed

fix git ignore

revert change in go.sum/go.mod

adding specific benchmark
---
 .gitignore              |  3 +++
 qb/select.go            | 24 ++++++++++++++++++++----
 qb/select_bench_test.go | 19 ++++++++++++++++++-
 qb/token.go             |  2 +-
 qb/update.go            | 12 ++++++++++--
 5 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/.gitignore b/.gitignore
index 6cbc40d..70033b9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,6 @@
 
 # Go vendor dir
 vendor
+
+# GoLand IDE
+.idea/
diff --git a/qb/select.go b/qb/select.go
index 14c71e6..9e4a36c 100644
--- a/qb/select.go
+++ b/qb/select.go
@@ -132,7 +132,11 @@ func (b *SelectBuilder) Json() *SelectBuilder {
 
 // Columns adds result columns to the query.
 func (b *SelectBuilder) Columns(columns ...string) *SelectBuilder {
-	b.columns = append(b.columns, columns...)
+	if len(b.columns) == 0 {
+		b.columns = columns
+	} else {
+		b.columns = append(b.columns, columns...)
+	}
 	return b
 }
 
@@ -143,21 +147,33 @@ func As(column, name string) string {
 
 // Distinct sets DISTINCT clause on the query.
 func (b *SelectBuilder) Distinct(columns ...string) *SelectBuilder {
-	b.distinct = append(b.distinct, columns...)
+	if len(b.where) == 0 {
+		b.distinct = columns
+	} else {
+		b.distinct = append(b.distinct, columns...)
+	}
 	return b
 }
 
 // Where adds an expression to the WHERE clause of the query. Expressions are
 // ANDed together in the generated CQL.
 func (b *SelectBuilder) Where(w ...Cmp) *SelectBuilder {
-	b.where = append(b.where, w...)
+	if len(b.where) == 0 {
+		b.where = w
+	} else {
+		b.where = append(b.where, w...)
+	}
 	return b
 }
 
 // GroupBy sets GROUP BY clause on the query. Columns must be a primary key,
 // this will automatically add the the columns as first selectors.
 func (b *SelectBuilder) GroupBy(columns ...string) *SelectBuilder {
-	b.groupBy = append(b.groupBy, columns...)
+	if len(b.groupBy) == 0 {
+		b.groupBy = columns
+	} else {
+		b.groupBy = append(b.groupBy, columns...)
+	}
 	return b
 }
 
diff --git a/qb/select_bench_test.go b/qb/select_bench_test.go
index 7932529..03451c7 100644
--- a/qb/select_bench_test.go
+++ b/qb/select_bench_test.go
@@ -9,6 +9,23 @@ import "testing"
 func BenchmarkSelectBuilder(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		Select("cycling.cyclist_name").Columns("id", "user_uuid", "firstname", "stars").Where(Eq("id")).ToCql()
+		Select("cycling.cyclist_name").
+			Columns("id", "user_uuid", "firstname", "surname", "stars").
+			Where(Eq("id")).
+			ToCql()
+	}
+}
+
+func BenchmarkSelectBuildAssign(b *testing.B) {
+	b.ResetTimer()
+	cols := []string{
+		"id", "user_uuid", "firstname",
+		"surname", "stars",
+	}
+	for i := 0; i < b.N; i++ {
+		Select("cycling.cyclist_name").
+			Columns(cols...).
+			Where(Eq("id")).
+			ToCql()
 	}
 }
diff --git a/qb/token.go b/qb/token.go
index 68e0b9d..64e62bc 100644
--- a/qb/token.go
+++ b/qb/token.go
@@ -14,7 +14,7 @@ type TokenBuilder []string
 
 // Token creates a new TokenBuilder.
 func Token(columns ...string) TokenBuilder {
-	return TokenBuilder(columns)
+	return columns
 }
 
 // Eq produces token(column)=token(?).
diff --git a/qb/update.go b/qb/update.go
index 72160e6..089e3ce 100644
--- a/qb/update.go
+++ b/qb/update.go
@@ -212,14 +212,22 @@ func (b *UpdateBuilder) removeValue(column string, value value) *UpdateBuilder {
 // Where adds an expression to the WHERE clause of the query. Expressions are
 // ANDed together in the generated CQL.
 func (b *UpdateBuilder) Where(w ...Cmp) *UpdateBuilder {
-	b.where = append(b.where, w...)
+	if len(b.where) == 0 {
+		b.where = w
+	} else {
+		b.where = append(b.where, w...)
+	}
 	return b
 }
 
 // If adds an expression to the IF clause of the query. Expressions are ANDed
 // together in the generated CQL.
 func (b *UpdateBuilder) If(w ...Cmp) *UpdateBuilder {
-	b._if = append(b._if, w...)
+	if len(b._if) == 0 {
+		b._if = w
+	} else {
+		b._if = append(b._if, w...)
+	}
 	return b
 }