Switched terminal width detection

Changed code to detect terminal width to be more operating system
independent.

Gopkg.toml

@@ -53,10 +53,6 @@
   branch = "master"
   name = "github.com/texttheater/golang-levenshtein"
 
-[[constraint]]
-  branch = "master"
-  name = "golang.org/x/sys"
-
 [prune]
   go-tests = true
   unused-packages = true

core/core.go

@@ -17,7 +17,6 @@ import (
 	"github.com/HeavyWombat/yaml"
 	"github.com/mitchellh/hashstructure"
 	"github.com/texttheater/golang-levenshtein/levenshtein"
-	"golang.org/x/sys/unix"
 )
 
 // Debug log output
@@ -132,23 +131,6 @@ func Plural(amount int, text ...string) string {
 	}
 }
 
-// GetTerminalSize return the current terminal size with width and height (columns and rows)
-func GetTerminalSize() (int, int) {
-	bounds, err := unix.IoctlGetWinsize(0, unix.TIOCGWINSZ)
-	if err != nil {
-		// TODO Add debug output that default terminal sizings were returned due to an error
-		return 80, 25
-	}
-
-	return int(bounds.Col), int(bounds.Row)
-}
-
-// GetTerminalWidth return the current terminal width
-func GetTerminalWidth() int {
-	width, _ := GetTerminalSize()
-	return width
-}
-
 func colorEachLine(color *color.Color, text string) string {
 	var buf bytes.Buffer
 

core/terminal_unix.go

@@ -0,0 +1,33 @@
+// +build !windows
+
+package core
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// GetTerminalWidth return the current terminal width
+func GetTerminalWidth() int {
+	const defaultWidth = 80
+
+	type winsize struct {
+		Row    uint16
+		Col    uint16
+		Xpixel uint16
+		Ypixel uint16
+	}
+
+	ws := &winsize{}
+	retCode, _, _ := syscall.Syscall(syscall.SYS_IOCTL,
+		uintptr(syscall.Stdin),
+		uintptr(syscall.TIOCGWINSZ),
+		uintptr(unsafe.Pointer(ws)))
+
+	if int(retCode) == -1 {
+		// TODO Add debug output that default terminal sizings were returned due
+		return defaultWidth
+	}
+
+	return int(ws.Col)
+}

core/terminal_windows.go

@@ -0,0 +1,9 @@
+// +build windows
+
+package core
+
+// GetTerminalWidth return the current terminal width
+func GetTerminalWidth() int {
+	// TODO Implement Windows terminal width if this is possible at all.
+	return 80
+}