From bfe176c5a991df7b9338953cb2a8cad7c7b4cfe4 Mon Sep 17 00:00:00 2001
From: David Vennik <david@indra-labs.org>
Date: Wed, 13 Sep 2023 11:37:39 +0100
Subject: [PATCH] first few types implemented

---
 pkg/splicer/i32/int32.go        | 16 +++++--
 pkg/splicer/magic/magic.go      | 82 +++++++++++++++++++++++++++++++++
 pkg/splicer/magic/magic_test.go |  1 +
 pkg/splicer/splicer.go          | 18 +++++---
 4 files changed, 107 insertions(+), 10 deletions(-)
 create mode 100644 pkg/splicer/magic/magic.go
 create mode 100644 pkg/splicer/magic/magic_test.go

diff --git a/pkg/splicer/i32/int32.go b/pkg/splicer/i32/int32.go
index 5e824080..0ff51dbf 100644
--- a/pkg/splicer/i32/int32.go
+++ b/pkg/splicer/i32/int32.go
@@ -18,6 +18,8 @@ func New() *S { return &S{b: make([]byte, Len)} }
 //
 // The remaining bytes, if any, are returned for further processing.
 func NewFrom(b []byte) (s *S, rem []byte) {
+	// If the bytes are less than Len the input is invalid and nil will be
+	// returned.
 	if len(b) < Len {
 		return
 	}
@@ -50,14 +52,20 @@ func (s *S) Write(by []byte) (out []byte) {
 func (s *S) Len() int { return len(s.b) }
 
 func (s *S) Get() (v interface{}) {
-	val := int32(binary.BigEndian.Uint32(s.b))
-	return &val
+	if len(s.b) >= Len {
+		val := int32(binary.BigEndian.Uint32(s.b))
+		return &val
+	}
+	return
 }
 
-func (s *S) Put(bits interface{}) interface{} {
+func (s *S) Put(v interface{}) interface{} {
+	if len(s.b) < Len {
+		s.b = make([]byte, Len)
+	}
 	var tv *int32
 	var ok bool
-	if tv, ok = bits.(*int32); ok {
+	if tv, ok = v.(*int32); ok {
 		binary.BigEndian.PutUint32(s.b[:Len], uint32(*tv))
 	}
 	return s
diff --git a/pkg/splicer/magic/magic.go b/pkg/splicer/magic/magic.go
new file mode 100644
index 00000000..1818dd43
--- /dev/null
+++ b/pkg/splicer/magic/magic.go
@@ -0,0 +1,82 @@
+package magic
+
+const Len = 4
+
+type Bytes struct {
+	bytes []byte
+}
+
+// New allocates bytes to store a new magic.Bytes in. Note that this allocates
+// memory.
+func New() *Bytes { return &Bytes{bytes: make([]byte, Len)} }
+
+// NewFrom creates a 32-bit integer from raw bytes, if the slice is at least Len
+// bytes long. This can be used to snip out an encoded segment which should
+// return a value from a call to Get.
+//
+// The remaining bytes, if any, are returned for further processing.
+func NewFrom(b []byte) (s *Bytes, rem []byte) {
+	if len(b) < Len {
+		return
+	}
+	// This slices the input, meaning no copy is required, only allocating the
+	// slice pointer.
+	s = &Bytes{bytes: b[:Len]}
+	if len(b) > Len {
+		rem = b[Len:]
+	}
+	return
+}
+
+func (m Bytes) Len() (l int) { return len(m.bytes) }
+
+func (m Bytes) Read() (o []byte) {
+	if len(m.bytes) >= Len {
+		o = m.bytes[:Len]
+	}
+	return
+}
+
+func (m Bytes) Write(b []byte) (o []byte) {
+	if len(b) >= Len {
+		m.bytes = b[:3]
+		// If there is more, return the excess.
+		if len(b) > Len {
+			o = b[Len:]
+		}
+	}
+	return
+}
+
+func (m Bytes) Get() (v interface{}) {
+	if len(m.bytes) >= Len {
+		val := string(m.bytes[:Len])
+		v = &val
+	}
+	return
+}
+
+func (m Bytes) Put(v interface{}) (o interface{}) {
+	var tv *string
+	var ok bool
+	if tv, ok = v.(*string); ok {
+		bytes := []byte(*tv)
+		if len(bytes) == Len {
+			m.bytes = bytes
+		}
+	}
+	return
+}
+
+// Assert takes an interface and if it is a duration.Time, returns the time.Time
+// value. If it is not the expected type, nil is returned.
+func Assert(v interface{}) (t *string) {
+	var tv *Bytes
+	var ok bool
+	if tv, ok = v.(*Bytes); ok {
+		tt := tv.Get()
+		// If this fails the return is nil, indicating failure.
+		t, _ = tt.(*string)
+	}
+	return
+}
diff --git a/pkg/splicer/magic/magic_test.go b/pkg/splicer/magic/magic_test.go
new file mode 100644
index 00000000..5ea4f8c7
--- /dev/null
+++ b/pkg/splicer/magic/magic_test.go
@@ -0,0 +1 @@
+package magic
diff --git a/pkg/splicer/splicer.go b/pkg/splicer/splicer.go
index 72f2f04a..b3efa75c 100644
--- a/pkg/splicer/splicer.go
+++ b/pkg/splicer/splicer.go
@@ -19,14 +19,14 @@ type Splice interface {
 	
 	// Len returns the number of bytes used to encode the Splice. This returns
 	// zero if no value has been encoded yet.
-	Len() int
+	Len() (l int)
 	
 	// Read returns the wire/storage form of the data.
-	Read() []byte
+	Read() (o []byte)
 	
 	// Write stores the decoded data from the head of the slice and returns the
 	// remainder. If the input bytes are not long enough, abort and return nil.
-	Write(b []byte) []byte
+	Write(b []byte) (o []byte)
 }
 
 // Accessor is a generic interface, for decoding and encoding runtime forms of
@@ -34,11 +34,17 @@ type Splice interface {
 // above.
 type Accessor interface {
 	
-	// Get returns the decoded value wrapped in an interface{}.
+	// Get returns the decoded value as a pointer wrapped in an interface{}.
 	Get() (v interface{})
 	
-	// Put
-	Put(v interface{}) interface{}
+	// Put inserts a pointer to a value that is expected to be the underlying
+	// type.
+	Put(v interface{}) (o interface{})
+}
+
+type SpliceAccessor interface {
+	Splice
+	Accessor
 }
 
 type Serializers []Splice