Merge branch 'feat-1'

README.md

@@ -79,6 +79,21 @@ res := format.Formatg("$1-$12")
 // res = "bc-bc"
 ```
 
+##### Use given `func(string) string` function as a source of values
+
+It is possible to use function like `os.Getenv` as a source of values. Use `format.Formatf` function for this:
+
+
+```go
+res := format.Formatf("${HOSTTYPE} ${COLUMNS}", os.Getenv)
+// res = "x86_64 80"
+```
+Check:
+
+![pic](Untitled.png)
+
+Of course, you can use every `func(string) string` function, not just `os.Getenv`
+
 ##### Date arithmetics
 ```go
 t := time.Date(2018, 1, 18, 22, 57, 37, 12, time.UTC)

context.go

@@ -28,3 +28,11 @@ func (ctx contextFromBuilder) GetFormatter(name string) (res Formatter, err erro
 	}
 	return
 }
+
+// contextFunc implementation of context using given func as a source of information
+type contextFunc func(string) string
+
+func (f contextFunc) GetFormatter(name string) (Formatter, error) {
+	value := f(name)
+	return stringFormatter(value), nil
+}

format.go

@@ -147,3 +147,13 @@ func Formatg(format string, data interface{}) string {
 	}
 	return res
 }
+
+// Formatf is a formatting where values are taken form given func(string) string function
+func Formatf(format string, data func(string) string) string {
+	ctx := contextFunc(data)
+	res, err := Format(format, ctx)
+	if err != nil {
+		panic(err)
+	}
+	return res
+}

format_test.go

@@ -112,7 +112,7 @@ func TestClarify(t *testing.T) {
 	}
 }
 
-func TestFormatf(t *testing.T) {
+func TestFormatp(t *testing.T) {
 	require.Equal(t, "a 2 4.5 2 2018", Formatp("${} ${} ${|1.1} ${1} ${|%Y}", "a", 2, 4.5, time.Date(2018, 10, 19, 18, 0, 5, 0, time.UTC)))
 	require.Equal(t, "a a", Formatp("$ $0", "a"))
 }
@@ -201,3 +201,37 @@ func TestReadmeDateArithmetics(t *testing.T) {
 	})
 	require.Equal(t, "2018-01-19 22:57:37", res)
 }
+
+func TestFormatf(t *testing.T) {
+	tests := []struct {
+		name   string
+		format string
+		data   func(string) string
+		want   string
+	}{
+		{
+			name:   "typical",
+			format: "${name} ${value} ${location} - ${fake}",
+			data: func(s string) string {
+				switch s {
+				case "name":
+					return "Denis"
+				case "value":
+					return "1k"
+				case "location":
+					return "cbx"
+				default:
+					return "<nil>"
+				}
+			},
+			want: "Denis 1k cbx - <nil>",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Formatf(tt.format, tt.data); got != tt.want {
+				t.Errorf("Formatf() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

go.mod

@@ -0,0 +1,12 @@
+module github.com/sirkon/go-format
+
+require (
+	github.com/fastly/go-utils v0.0.0-20180712184237-d95a45783239 // indirect
+	github.com/jehiah/go-strftime v0.0.0-20171201141054-1d33003b3869 // indirect
+	github.com/lestrrat/go-envload v0.0.0-20180220120943-6ed08b54a570 // indirect
+	github.com/lestrrat/go-strftime v0.0.0-20180220042222-ba3bf9c1d042
+	github.com/pkg/errors v0.8.1 // indirect
+	github.com/stretchr/testify v1.3.0
+	github.com/tebeka/strftime v0.0.0-20140926081919-3f9c7761e312 // indirect
+	golang.org/x/net v0.0.0-20190119204137-ed066c81e75e // indirect
+)