Do a large chunk of the move to go

This commit moves a huge chunk of the code to go. The TODO.md document
indicates what is left to be done.

internal/logging/level.go

@@ -0,0 +1,59 @@
+package logging
+
+import (
+	"sync"
+
+	"github.com/tkw1536/goprogram/stream"
+)
+
+var logLevelMutex sync.Mutex
+var logLevelMap = make(map[uintptr]int)
+
+func getIndent(io stream.IOStream) int {
+	logLevelMutex.Lock()
+	defer logLevelMutex.Unlock()
+
+	id, ok := logID(io)
+	if !ok {
+		return 0
+	}
+
+	return logLevelMap[id]
+}
+
+func incIndent(io stream.IOStream) int {
+	logLevelMutex.Lock()
+	defer logLevelMutex.Unlock()
+
+	id, ok := logID(io)
+	if !ok { // if we don't have an id, then inc statically returns 1
+		return 1
+	}
+
+	logLevelMap[id]++
+	return logLevelMap[id]
+}
+
+func decIndent(io stream.IOStream) int {
+	logLevelMutex.Lock()
+	defer logLevelMutex.Unlock()
+	id, ok := logID(io)
+
+	if !ok { // if we don't have an id, then dec statically returns 0
+		return 0
+	}
+
+	logLevelMap[id]--
+	if logLevelMap[id] < 0 {
+		panic("DecLogIdent: decrease below 0")
+	}
+	return logLevelMap[id]
+}
+
+func logID(io stream.IOStream) (uintptr, bool) {
+	file, ok := io.Stdin.(interface{ Fd() uintptr })
+	if !ok {
+		return 0, false
+	}
+	return file.Fd(), true
+}