From 5d8a72a8c08a407bcc69edfc0c5372f84525605f Mon Sep 17 00:00:00 2001
From: OpenIM-Gordon <1432970085@qq.com>
Date: Thu, 26 Dec 2024 16:56:42 +0800
Subject: [PATCH] feat: add intersection func. (#187)

* optimization: slice sub.

* fix: rpc logger add more detail info.

* feat: add msg gateway error.

* refactor: separate functions with error containing message and error with only stack trace.

* feat: add stdout and stderr info.

* feat: add strings and sql log.

* feat: add copy function.

* feat: add strings function.

* feat: add strings function.

* feat: add strings function.

* feat: print version filed.

* fix: version update.

* refactor: change go mod name.

* refactor: change go mod name.

* refactor: change go mod name.

* refactor: log change.

* refactor: log change.

* refactor: log change.

* fix: log  kv do not print origin pointer.

* feat: log add panic level.

* feat: add intersection func.
---
 utils/datautil/datautil.go | 44 ++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/utils/datautil/datautil.go b/utils/datautil/datautil.go
index 4117031..889af46 100644
--- a/utils/datautil/datautil.go
+++ b/utils/datautil/datautil.go
@@ -15,14 +15,16 @@
 package datautil
 
 import (
-	"github.com/jinzhu/copier"
-	"github.com/openimsdk/tools/db/pagination"
-	"github.com/openimsdk/tools/errs"
-	"github.com/openimsdk/tools/utils/jsonutil"
 	"math/rand"
 	"reflect"
 	"sort"
 	"time"
+
+	"github.com/jinzhu/copier"
+
+	"github.com/openimsdk/tools/db/pagination"
+	"github.com/openimsdk/tools/errs"
+	"github.com/openimsdk/tools/utils/jsonutil"
 )
 
 // SliceSubFuncs returns elements in slice a that are not present in slice b (a - b) and remove duplicates.
@@ -51,6 +53,40 @@ func SliceSubFuncs[T, V any, E comparable](a []T, b []V, fna func(i T) E, fnb fu
 	return rs
 }
 
+// SliceIntersectFuncs returns the intersection (a ∩ b) of slices a and b, removing duplicates.
+// The equality of elements is determined by the custom functions fna and fnb provided for each slice.
+func SliceIntersectFuncs[T, V any, E comparable](a []T, b []V, fna func(i T) E, fnb func(i V) E) []T {
+	// If b is empty, return an empty slice
+	if len(b) == 0 {
+		return nil
+	}
+
+	// Map the elements of b to a set for fast lookup
+	k := make(map[E]struct{})
+	for _, item := range b {
+		k[fnb(item)] = struct{}{}
+	}
+
+	// Create a slice to store the intersection result
+	rs := make([]T, 0, len(a))
+	// Map for deduplication
+	t := make(map[E]struct{})
+
+	// Iterate over slice a and find the common elements with b
+	for _, item := range a {
+		// Get the comparison value of the element from slice a
+		e := fna(item)
+		// If the element exists in both a and b, and hasn't been added yet, add it to the result
+		if _, ok := k[e]; ok && t[e] == struct{}{} {
+			rs = append(rs, item)
+			t[e] = struct{}{}
+		}
+	}
+
+	// Return the intersection slice
+	return rs
+}
+
 // SliceSubFunc returns elements in slice a that are not present in slice b (a - b) and remove duplicates.
 // Determine if elements are equal based on the result returned by fn.
 func SliceSubFunc[T any, E comparable](a, b []T, fn func(i T) E) []T {