From 54913b21c996c989f9a98acb94cbacdb8758610d Mon Sep 17 00:00:00 2001
From: Bel LaPointe <breel@qualtrics.com>
Date: Wed, 25 Oct 2023 08:21:16 -0600
Subject: [PATCH] deltas.Group(GroupName("^[^:]*"))

---
 ledger/deltas.go      |  8 ++++++++
 ledger/deltas_test.go | 26 ++++++++++++++++++++++++++
 ledger/group.go       |  9 +++++++++
 3 files changed, 43 insertions(+)

diff --git a/ledger/deltas.go b/ledger/deltas.go
index 31d598b..0f1b3a4 100644
--- a/ledger/deltas.go
+++ b/ledger/deltas.go
@@ -6,6 +6,14 @@ import (
 
 type Deltas []Delta
 
+func (deltas Deltas) Group(group ...Group) Deltas {
+	result := make(Deltas, 0, len(deltas))
+	for i := range deltas {
+		result = append(result, Groups(group).Each(deltas[i]))
+	}
+	return result
+}
+
 func (deltas Deltas) Like(like ...Like) Deltas {
 	result := make(Deltas, 0, len(deltas))
 	for i := range deltas {
diff --git a/ledger/deltas_test.go b/ledger/deltas_test.go
index 3f13859..859e639 100644
--- a/ledger/deltas_test.go
+++ b/ledger/deltas_test.go
@@ -3,6 +3,32 @@ package ledger
 import "testing"
 
 func TestDeltas(t *testing.T) {
+	t.Run("Groups", func(t *testing.T) {
+		deltas := Deltas{
+			{Name: "a1"},
+			{Name: "b1"},
+			{Name: "b2"},
+			{Name: "b3"},
+		}
+
+		deltas = deltas.Group(GroupName("^."))
+		if len(deltas) != 4 {
+			t.Error(len(deltas))
+		}
+		if deltas[0].Name != "a" {
+			t.Error(deltas[0].Name)
+		}
+		if deltas[1].Name != "b" {
+			t.Error(deltas[1].Name)
+		}
+		if deltas[2].Name != "b" {
+			t.Error(deltas[2].Name)
+		}
+		if deltas[3].Name != "b" {
+			t.Error(deltas[3].Name)
+		}
+	})
+
 	t.Run("balances", func(t *testing.T) {
 		deltas := Deltas{
 			{Name: "a", Value: 0},
diff --git a/ledger/group.go b/ledger/group.go
index 82ea816..abe5b83 100644
--- a/ledger/group.go
+++ b/ledger/group.go
@@ -4,6 +4,15 @@ import "regexp"
 
 type Group func(Delta) Delta
 
+type Groups []Group
+
+func (groups Groups) Each(d Delta) Delta {
+	for i := range groups {
+		d = groups[i](d)
+	}
+	return d
+}
+
 func GroupDate(pattern string) Group {
 	p := regexp.MustCompile(pattern)
 	return func(d Delta) Delta {