Improved truncation functionality for terminals of smaller width

aws.go

@@ -1,15 +1,14 @@
 package main
 
 import (
-	"fmt"
 	"os"
 )
 
 func segmentAWS(p *powerline) {
 	profile, _ := os.LookupEnv("AWS_PROFILE")
 	if profile != "" {
 		p.appendSegment("aws", segment{
-			content:    fmt.Sprintf(" %s ", profile),
+			content:    profile,
 			foreground: p.theme.AWSFg,
 			background: p.theme.AWSBg,
 		})

defaults.go

@@ -43,21 +43,21 @@ var symbolTemplates = map[string]Symbols{
 var shellInfos = map[string]ShellInfo{
 	"bash": {
 		colorTemplate:    "\\[\\e%s\\]",
-		rootIndicator:    " \\$ ",
+		rootIndicator:    "\\$",
 		escapedBackslash: `\\\\`,
 		escapedBacktick:  "\\`",
 		escapedDollar:    `\$`,
 	},
 	"zsh": {
 		colorTemplate:    "%%{\u001b%s%%}",
-		rootIndicator:    " %# ",
+		rootIndicator:    "%#",
 		escapedBackslash: `\\`,
 		escapedBacktick:  "\\`",
 		escapedDollar:    `\$`,
 	},
 	"bare": {
 		colorTemplate: "%s",
-		rootIndicator:    " $ ",
+		rootIndicator:    "$",
 		escapedBackslash: `\`,
 		escapedBacktick:  "`",
 		escapedDollar:    `$`,

main.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"github.com/mattn/go-runewidth"
 	"io/ioutil"
 	"os"
 	"strings"
@@ -23,23 +24,29 @@ type segment struct {
 	separator           string
 	separatorForeground uint8
 	priority            int
+	width               int
 }
 
 type args struct {
-	CwdMode            *string
-	CwdMaxDepth        *int
-	CwdMaxDirSize      *int
-	ColorizeHostname   *bool
-	EastAsianWidth     *bool
-	PromptOnNewLine    *bool
-	Mode               *string
-	Theme              *string
-	Shell              *string
-	Modules            *string
-	Priority           *string
-	MaxWidthPercentage *int
-	IgnoreRepos        *string
-	PrevError          *int
+	CwdMode              *string
+	CwdMaxDepth          *int
+	CwdMaxDirSize        *int
+	ColorizeHostname     *bool
+	EastAsianWidth       *bool
+	PromptOnNewLine      *bool
+	Mode                 *string
+	Theme                *string
+	Shell                *string
+	Modules              *string
+	Priority             *string
+	MaxWidthPercentage   *int
+	TruncateSegmentWidth *int
+	IgnoreRepos          *string
+	PrevError            *int
+}
+
+func (s segment) computeWidth() int {
+	return runewidth.StringWidth(s.content) + runewidth.StringWidth(s.separator) + 2
 }
 
 func warn(msg string) {
@@ -139,6 +146,10 @@ func main() {
 			50,
 			"Maximum width of the shell that the prompt may use, in percent. Setting this to 0 disables the shrinking subsystem.\n"+
 				"       "),
+		TruncateSegmentWidth: flag.Int("truncate-segment-width",
+			16,
+			"Minimum width of a segment, segments longer than this will be shortened if space is limited. Setting this to 0 disables it.\n"+
+				"       "),
 		PrevError: flag.Int("error", 0,
 			"Exit code of previously executed command"),
 		IgnoreRepos: flag.String("ignore-repos",

powerline.go

@@ -73,12 +73,13 @@ func (p *powerline) appendSegment(origin string, segment segment) {
 		segment.separatorForeground = segment.background
 	}
 	priority, _ := p.priorities[origin]
-	segment.priority = priority
+	segment.priority += priority
+	segment.width = segment.computeWidth()
 	p.Segments = append(p.Segments, segment)
 }
 
 func termWidth() int {
-	width, _, err := terminal.GetSize(int(os.Stdout.Fd()))
+	termWidth, _, err := terminal.GetSize(int(os.Stdout.Fd()))
 	if err != nil {
 		shellMaxLengthStr, found := os.LookupEnv("COLUMNS")
 		if !found {
@@ -90,10 +91,10 @@ func termWidth() int {
 			return 80 // Otherwise 0 default.
 		}
 
-		width = int(shellMaxLength64)
+		termWidth = int(shellMaxLength64)
 	}
 
-	return width
+	return termWidth
 }
 
 func (p *powerline) draw() string {
@@ -103,11 +104,40 @@ func (p *powerline) draw() string {
 
 	shellActualLength := 0
 	if shellMaxLength > 0 {
-		rlen := runewidth.StringWidth
-
 		for _, segment := range p.Segments {
-			shellActualLength += rlen(segment.content) + rlen(segment.separator)
+			shellActualLength += segment.width
+		}
+		if shellActualLength > shellMaxLength && *p.args.TruncateSegmentWidth > 0 {
+			minPriorityNotTruncated := MaxInteger
+			minPriorityNotTruncatedSegmentId := -1
+			for idx, segment := range p.Segments {
+				if segment.width > *p.args.TruncateSegmentWidth && segment.priority < minPriorityNotTruncated {
+					minPriorityNotTruncated = segment.priority
+					minPriorityNotTruncatedSegmentId = idx
+				}
+			}
+			for minPriorityNotTruncatedSegmentId != -1 && shellActualLength > shellMaxLength {
+				segment := p.Segments[minPriorityNotTruncatedSegmentId]
+
+				shellActualLength -= segment.width
+
+				segment.content = runewidth.Truncate(segment.content, *p.args.TruncateSegmentWidth-runewidth.StringWidth(segment.separator)-5, "")
+				segment.width = segment.computeWidth()
+
+				p.Segments = append(append(p.Segments[:minPriorityNotTruncatedSegmentId], segment), p.Segments[minPriorityNotTruncatedSegmentId+1:]...)
+				shellActualLength += segment.width
+
+				minPriorityNotTruncated = MaxInteger
+				minPriorityNotTruncatedSegmentId = -1
+				for idx, segment := range p.Segments {
+					if segment.width > *p.args.TruncateSegmentWidth && segment.priority < minPriorityNotTruncated {
+						minPriorityNotTruncated = segment.priority
+						minPriorityNotTruncatedSegmentId = idx
+					}
+				}
+			}
 		}
+
 		for shellActualLength > shellMaxLength {
 			minPriority := MaxInteger
 			minPrioritySegmentId := -1
@@ -120,7 +150,7 @@ func (p *powerline) draw() string {
 			if minPrioritySegmentId != -1 {
 				segment := p.Segments[minPrioritySegmentId]
 				p.Segments = append(p.Segments[:minPrioritySegmentId], p.Segments[minPrioritySegmentId+1:]...)
-				shellActualLength -= rlen(segment.content) + rlen(segment.separator)
+				shellActualLength -= segment.width
 			}
 		}
 	}
@@ -137,7 +167,9 @@ func (p *powerline) draw() string {
 
 		buffer.WriteString(p.fgColor(segment.foreground))
 		buffer.WriteString(p.bgColor(segment.background))
+		buffer.WriteRune(' ')
 		buffer.WriteString(segment.content)
+		buffer.WriteRune(' ')
 		buffer.WriteString(separatorBackground)
 		buffer.WriteString(p.fgColor(segment.separatorForeground))
 		buffer.WriteString(segment.separator)

segment-cwd.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"os"
 	"strings"
 )
@@ -13,6 +12,7 @@ type pathSegment struct {
 	home     bool
 	root     bool
 	ellipsis bool
+	priority int
 }
 
 func cwdToPathSegments(cwd string) []pathSegment {
@@ -85,7 +85,7 @@ func segmentCwd(p *powerline) {
 		}
 
 		p.appendSegment("cwd", segment{
-			content:    fmt.Sprintf(" %s ", cwd),
+			content:    cwd,
 			foreground: p.theme.CwdFg,
 			background: p.theme.PathBg,
 		})
@@ -107,18 +107,25 @@ func segmentCwd(p *powerline) {
 				}
 				firstPart := pathSegments[:nBefore]
 				secondPart := pathSegments[len(pathSegments)+nBefore-maxDepth:]
-				pathSegments = append(append(firstPart, pathSegment{
+				pathSegments = make([]pathSegment, 0)
+				for _, segment := range firstPart {
+					segment.priority = -2
+					pathSegments = append(pathSegments, segment)
+				}
+				pathSegments = append(pathSegments, pathSegment{
+					priority: -1,
 					path:     ellipsis,
 					ellipsis: true,
-				}), secondPart...)
+				})
+				pathSegments = append(pathSegments, secondPart...)
 			}
 
 			for idx, pathSegment := range pathSegments {
 				isLastDir := idx == len(pathSegments)-1
 				foreground, background := getColor(p, pathSegment, isLastDir)
 
 				segment := segment{
-					content:    fmt.Sprintf(" %s ", escapeVariables(p, maybeShortenName(p, pathSegment.path))),
+					content:    escapeVariables(p, maybeShortenName(p, pathSegment.path)),
 					foreground: foreground,
 					background: background,
 				}

segment-docker.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"net/url"
 	"os"
 )
@@ -22,7 +21,7 @@ func segmentDocker(p *powerline) {
 
 	if docker != "" {
 		p.appendSegment("docker", segment{
-			content:    fmt.Sprintf(" %s ", docker),
+			content:    docker,
 			foreground: p.theme.DockerMachineFg,
 			background: p.theme.DockerMachineBg,
 		})

segment-dotenv.go

@@ -8,7 +8,7 @@ func segmentDotEnv(p *powerline) {
 	stat, err := os.Stat(".env")
 	if err == nil && !stat.IsDir() {
 		p.appendSegment("dotenv", segment{
-			content:    " \u2235 ",
+			content:    "\u2235",
 			foreground: p.theme.DotEnvFg,
 			background: p.theme.DotEnvBg,
 		})

segment-exitcode.go

@@ -67,7 +67,7 @@ func segmentExitCode(p *powerline) {
 	if *p.args.PrevError != 0 {
 		meaning := getMeaningFromExitCode(*p.args.PrevError)
 		p.appendSegment("exit", segment{
-			content:    fmt.Sprintf(" %s ", meaning),
+			content:    meaning,
 			foreground: p.theme.CmdFailedFg,
 			background: p.theme.CmdFailedBg,
 		})

segment-git.go

@@ -25,7 +25,7 @@ func (r repoStats) dirty() bool {
 func addRepoStatsSegment(p *powerline, nChanges int, symbol string, foreground uint8, background uint8) {
 	if nChanges > 0 {
 		p.appendSegment("git-status", segment{
-			content:    fmt.Sprintf(" %d%s ", nChanges, symbol),
+			content:    fmt.Sprintf("%d%s", nChanges, symbol),
 			foreground: foreground,
 			background: background,
 		})
@@ -167,7 +167,7 @@ func segmentGit(p *powerline) {
 	}
 
 	p.appendSegment("git-branch", segment{
-		content:    fmt.Sprintf(" %s ", branch),
+		content:    branch,
 		foreground: foreground,
 		background: background,
 	})

segment-gitlite.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"strings"
 )
 
@@ -32,7 +31,7 @@ func segmentGitLite(p *powerline) {
 	}
 
 	p.appendSegment("git-branch", segment{
-		content:    fmt.Sprintf(" %s ", branch),
+		content:    branch,
 		foreground: p.theme.RepoCleanFg,
 		background: p.theme.RepoCleanBg,
 	})

segment-hg.go

@@ -52,12 +52,12 @@ func segmentHg(p *powerline) {
 				extra += "!"
 			}
 
-			content = fmt.Sprintf(" %s %s ", branch, extra)
+			content = fmt.Sprintf("%s %s", branch, extra)
 		} else {
 			foreground = p.theme.RepoCleanFg
 			background = p.theme.RepoCleanBg
 
-			content = fmt.Sprintf(" %s ", branch)
+			content = fmt.Sprintf(branch)
 		}
 
 		p.appendSegment("hg", segment{

segment-hostname.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"crypto/md5"
-	"fmt"
 	"os"
 	"strings"
 )
@@ -23,18 +22,18 @@ func segmentHost(p *powerline) {
 	var foreground, background uint8
 	if *p.args.ColorizeHostname {
 		hostName := getHostName()
-		hostPrompt = fmt.Sprintf(" %s ", hostName)
+		hostPrompt = hostName
 
 		hash := getMd5(hostName)
 		background = hash[0]
 		foreground = p.theme.HostnameColorizedFgMap[background]
 	} else {
 		if *p.args.Shell == "bash" {
-			hostPrompt = " \\h "
+			hostPrompt = "\\h"
 		} else if *p.args.Shell == "zsh" {
-			hostPrompt = " %m "
+			hostPrompt = "%m"
 		} else {
-			hostPrompt = fmt.Sprintf(" %s ", getHostName())
+			hostPrompt = getHostName()
 		}
 
 		foreground = p.theme.HostnameFg

segment-jobs.go

@@ -23,7 +23,7 @@ func segmentJobs(p *powerline) {
 
 	if nJobs > 0 {
 		p.appendSegment("jobs", segment{
-			content:    fmt.Sprintf(" %d ", nJobs),
+			content:    fmt.Sprintf("%d", nJobs),
 			foreground: p.theme.JobsFg,
 			background: p.theme.JobsBg,
 		})

segment-perlbrew.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"os"
 	"path"
 )
@@ -14,7 +13,7 @@ func segmentPerlbrew(p *powerline) {
 
 	envName := path.Base(env)
 	p.appendSegment("perlbrew", segment{
-		content:    fmt.Sprintf(" %s ", envName),
+		content:    envName,
 		foreground: p.theme.PerlbrewFg,
 		background: p.theme.PerlbrewBg,
 	})