eve

commit de5eea1809ad05e71312899f669ed25141c1ed89
Author: Yongbin Kim <iam@yongbin.kim>
Date:   Fri,  3 Nov 2023 12:52:56 +0900

First commit

Diffstat:
A
.gitignore
 | 
23
+++++++++++++++++++++++
A
LICENSE
 | 
15
+++++++++++++++
A
eve.go
 | 
65
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
go.mod
 | 
5
+++++
A
go.sum
 | 
2
++

5 files changed, 110 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,23 @@
+# Allowlisting gitignore template for GO projects prevents us
+# from adding various unwanted local files, such as generated
+# files, developer configurations or IDE-specific files etc.
+#
+# Recommended: Go.AllowList.gitignore
+
+# Ignore everything
+*
+
+# But not these files...
+!/.gitignore
+
+!*.go
+!go.sum
+!go.mod
+
+!README.md
+!LICENSE
+
+# !Makefile
+
+# ...even if they are in subdirectories
+!*/
diff --git a/LICENSE b/LICENSE
@@ -0,0 +1,15 @@
+ISC License
+
+Copyright (c) 2023 Yongbin Kim
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
diff --git a/eve.go b/eve.go
@@ -0,0 +1,65 @@
+package eve
+
+import (
+	"context"
+	"sync"
+
+	"go.uber.org/multierr"
+)
+
+type (
+	eventFn[E any]  func(ctx context.Context, e E) error
+	eventMap[E any] map[uint64]eventFn[E]
+)
+
+type Event[E any] interface {
+	On(fn eventFn[E]) func()
+	Emit(ctx context.Context, event E) error
+}
+
+type event[E any] struct {
+	mu       sync.Mutex
+	acc      uint64
+	handlers map[uint64]eventFn[E]
+}
+
+func New[E any]() Event[E] {
+	return &event[E]{
+		handlers: make(eventMap[E]),
+	}
+}
+
+func (e *event[E]) On(fn eventFn[E]) func() {
+	e.mu.Lock()
+
+	id := e.acc
+	e.acc++
+
+	e.handlers[id] = fn
+
+	e.mu.Unlock()
+
+	canceled := false
+	return func() {
+		if canceled {
+			return
+		}
+
+		e.mu.Lock()
+		delete(e.handlers, id)
+		e.mu.Unlock()
+	}
+}
+
+func (e *event[E]) Emit(ctx context.Context, event E) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	var err error
+
+	for _, fn := range e.handlers {
+		multierr.Append(err, fn(ctx, event))
+	}
+
+	return err
+}
diff --git a/go.mod b/go.mod
@@ -0,0 +1,5 @@
+module go.lair.cx/eve
+
+go 1.21.2
+
+require go.uber.org/multierr v1.11.0 // indirect
diff --git a/go.sum b/go.sum
@@ -0,0 +1,2 @@
+go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
+go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=