setup CI

.github/workflows/check.yaml

@@ -0,0 +1,8 @@
+on: [push, pull_request]
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/setup-go@v2
+    - uses: actions/checkout@v2
+    - run: make ci-check

.gitignore

@@ -1 +1,2 @@
+.bin
 .coverprofile

Makefile

@@ -3,10 +3,10 @@ SOURCES = $(shell find . -name "*.go")
 default: build
 
 build:
-	go build ./...
+	@go build ./...
 
 check:
-	go test -count 1 ./...
+	@go test -count 1 ./...
 
 imports:
 	@goimports -w $(SOURCES)
@@ -15,10 +15,13 @@ fmt:
 	@gofmt -w -s $(SOURCES)
 
 .coverprofile: $(SOURCES)
-	go test -count 1 -coverprofile .coverprofile
+	@go test -count 1 -coverprofile .coverprofile
 
 cover: .coverprofile
-	go tool cover -func .coverprofile
+	@go tool cover -func .coverprofile
 
 showcover: .coverprofile
-	go tool cover -html .coverprofile
+	@go tool cover -html .coverprofile
+
+check-fmt:
+	@! ( gofmt -s -l . | grep . )

fprint.go

@@ -65,6 +65,7 @@ func nodeLen(t int, n node) node {
 		return n
 	}
 
+	// measure all parts:
 	for i := range n.parts {
 		switch pt := n.parts[i].(type) {
 		case node:
@@ -76,6 +77,7 @@ func nodeLen(t int, n node) node {
 		}
 	}
 
+	// measure the unwrapped length:
 	for _, p := range n.parts {
 		switch pt := p.(type) {
 		case node:
@@ -94,6 +96,7 @@ func nodeLen(t int, n node) node {
 		}
 	}
 
+	// measure the wrapped and the fully wrapped length:
 	var w, f int
 	for _, p := range n.parts {
 		switch pt := p.(type) {
@@ -192,6 +195,7 @@ func wrapNode(t, cf0, c0, c1 int, n node) node {
 		return n
 	}
 
+	// otherwise, we need to wrap the node:
 	n.wrap = true
 
 	// We assume here that an str is always contained
@@ -203,6 +207,10 @@ func wrapNode(t, cf0, c0, c1 int, n node) node {
 		return n
 	}
 
+	// before iterating over the parts, take a copy of
+	// the available column width and modify only the
+	// copy, to support trackback.
+	//
 	cc0, cc1 := c0, c1
 	lastWrapperIndex := -1
 	var trackBack bool

sprint_test.go

@@ -1004,9 +1004,9 @@ func TestLongString(t *testing.T) {
 
 func TestCyclicReferences(t *testing.T) {
 	t.Run("slice", func(t *testing.T) {
-		const expect = `r0=[]{r0}`
-		l := []interface{}{"foo"}
-		l[0] = l
+		const expect = `r0=[]{"foo", r0}`
+		l := []interface{}{"foo", "bar"}
+		l[1] = l
 		s := Sprint(l)
 		if s != expect {
 			t.Fatalf("expected: %s, got: %s", expect, s)