context: envsubst

context.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/rsteube/carapace/third_party/github.com/drone/envsubst"
 	"github.com/rsteube/carapace/third_party/golang.org/x/sys/execabs"
 )
 
@@ -23,6 +24,24 @@ type Context struct {
 	Dir string
 }
 
+// LookupEnv retrieves the value of the environment variable named by the key.
+func (c *Context) LookupEnv(key string) (string, bool) {
+	prefix := key + "="
+	for i := len(c.Env) - 1; i >= 0; i-- {
+		if env := c.Env[i]; strings.HasPrefix(env, prefix) {
+			return strings.SplitN(env, "=", 2)[1], true
+		}
+	}
+	return "", false
+
+}
+
+// Getenv retrieves the value of the environment variable named by the key.
+func (c *Context) Getenv(key string) string {
+	v, _ := c.LookupEnv(key)
+	return v
+}
+
 // Setenv sets the value of the environment variable named by the key.
 func (c *Context) Setenv(key, value string) {
 	if c.Env == nil {
@@ -31,6 +50,10 @@ func (c *Context) Setenv(key, value string) {
 	c.Env = append(c.Env, fmt.Sprintf("%v=%v", key, value))
 }
 
+func (c *Context) Envsubst(s string) (string, error) {
+	return envsubst.Eval(s, c.Getenv)
+}
+
 // Command returns the Cmd struct to execute the named program with the given arguments.
 // Env and Dir are set using the Context.
 // See exec.Command for most details.

context_test.go

@@ -62,3 +62,50 @@ func TestContextAbs(t *testing.T) {
 	}
 
 }
+
+func TestEnv(t *testing.T) {
+	c := Context{}
+	if c.Getenv("example") != "" {
+		t.Fail()
+	}
+	if v, exist := c.LookupEnv("example"); v != "" || exist {
+		t.Fail()
+	}
+
+	c.Setenv("example", "value")
+	if c.Getenv("example") != "value" {
+		t.Fail()
+	}
+	if v, exist := c.LookupEnv("example"); v != "value" || !exist {
+		t.Fail()
+	}
+
+	c.Setenv("example", "newvalue")
+	if c.Getenv("example") != "newvalue" {
+		t.Fail()
+	}
+	if v, exist := c.LookupEnv("example"); v != "newvalue" || !exist {
+		t.Fail()
+	}
+}
+
+func TestEnvsubst(t *testing.T) {
+	c := Context{}
+
+	if s, err := c.Envsubst("start${example}end"); s != "startend" || err != nil {
+		t.Fail()
+	}
+
+	if s, err := c.Envsubst("start${example:-default}end"); s != "startdefaultend" || err != nil {
+		t.Fail()
+	}
+
+	c.Setenv("example", "value")
+	if s, err := c.Envsubst("start${example}end"); s != "startvalueend" || err != nil {
+		t.Fail()
+	}
+
+	if s, err := c.Envsubst("start${example:-default}end"); s != "startvalueend" || err != nil {
+		t.Fail()
+	}
+}

third_party/github.com/drone/envsubst/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2017 drone.io
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

third_party/github.com/drone/envsubst/eval.go

@@ -0,0 +1,19 @@
+package envsubst
+
+import "os"
+
+// Eval replaces ${var} in the string based on the mapping function.
+func Eval(s string, mapping func(string) string) (string, error) {
+	t, err := Parse(s)
+	if err != nil {
+		return s, err
+	}
+	return t.Execute(mapping)
+}
+
+// EvalEnv replaces ${var} in the string according to the values of the
+// current environment variables. References to undefined variables are
+// replaced by the empty string.
+func EvalEnv(s string) (string, error) {
+	return Eval(s, os.Getenv)
+}

third_party/github.com/drone/envsubst/eval_test.go

@@ -0,0 +1,228 @@
+package envsubst
+
+import "testing"
+
+// test cases sourced from tldp.org
+// http://www.tldp.org/LDP/abs/html/parameter-substitution.html
+
+func TestExpand(t *testing.T) {
+	var expressions = []struct {
+		params map[string]string
+		input  string
+		output string
+	}{
+		// text-only
+		{
+			params: map[string]string{},
+			input:  "abcdEFGH28ij",
+			output: "abcdEFGH28ij",
+		},
+		// length
+		{
+			params: map[string]string{"var01": "abcdEFGH28ij"},
+			input:  "${#var01}",
+			output: "12",
+		},
+		// uppercase first
+		{
+			params: map[string]string{"var01": "abcdEFGH28ij"},
+			input:  "${var01^}",
+			output: "AbcdEFGH28ij",
+		},
+		// uppercase
+		{
+			params: map[string]string{"var01": "abcdEFGH28ij"},
+			input:  "${var01^^}",
+			output: "ABCDEFGH28IJ",
+		},
+		// lowercase first
+		{
+			params: map[string]string{"var01": "ABCDEFGH28IJ"},
+			input:  "${var01,}",
+			output: "aBCDEFGH28IJ",
+		},
+		// lowercase
+		{
+			params: map[string]string{"var01": "ABCDEFGH28IJ"},
+			input:  "${var01,,}",
+			output: "abcdefgh28ij",
+		},
+		// substring with position
+		{
+			params: map[string]string{"path_name": "/home/bozo/ideas/thoughts.for.today"},
+			input:  "${path_name:11}",
+			output: "ideas/thoughts.for.today",
+		},
+		// substring with position and length
+		{
+			params: map[string]string{"path_name": "/home/bozo/ideas/thoughts.for.today"},
+			input:  "${path_name:11:5}",
+			output: "ideas",
+		},
+		// default not used
+		{
+			params: map[string]string{"var": "abc"},
+			input:  "${var=xyz}",
+			output: "abc",
+		},
+		// default used
+		{
+			params: map[string]string{},
+			input:  "${var=xyz}",
+			output: "xyz",
+		},
+		{
+			params: map[string]string{"default_var": "foo"},
+			input:  "something ${var=${default_var}}",
+			output: "something foo",
+		},
+		{
+			params: map[string]string{"default_var": "foo1"},
+			input:  `foo: ${var=${default_var}-suffix}`,
+			output: "foo: foo1-suffix",
+		},
+		{
+			params: map[string]string{"default_var": "foo1"},
+			input:  `foo: ${var=prefix${default_var}-suffix}`,
+			output: "foo: prefixfoo1-suffix",
+		},
+		{
+			params: map[string]string{},
+			input:  "${var:=xyz}",
+			output: "xyz",
+		},
+		// replace suffix
+		{
+			params: map[string]string{"stringZ": "abcABC123ABCabc"},
+			input:  "${stringZ/%abc/XYZ}",
+			output: "abcABC123ABCXYZ",
+		},
+		// replace prefix
+		{
+			params: map[string]string{"stringZ": "abcABC123ABCabc"},
+			input:  "${stringZ/#abc/XYZ}",
+			output: "XYZABC123ABCabc",
+		},
+		// replace all
+		{
+			params: map[string]string{"stringZ": "abcABC123ABCabc"},
+			input:  "${stringZ//abc/xyz}",
+			output: "xyzABC123ABCxyz",
+		},
+		// replace first
+		{
+			params: map[string]string{"stringZ": "abcABC123ABCabc"},
+			input:  "${stringZ/abc/xyz}",
+			output: "xyzABC123ABCabc",
+		},
+		// delete shortest match prefix
+		{
+			params: map[string]string{"filename": "bash.string.txt"},
+			input:  "${filename#*.}",
+			output: "string.txt",
+		},
+		{
+			params: map[string]string{"filename": "path/to/file"},
+			input:  "${filename#*/}",
+			output: "to/file",
+		},
+		{
+			params: map[string]string{"filename": "/path/to/file"},
+			input:  "${filename#*/}",
+			output: "path/to/file",
+		},
+		// delete longest match prefix
+		{
+			params: map[string]string{"filename": "bash.string.txt"},
+			input:  "${filename##*.}",
+			output: "txt",
+		},
+		{
+			params: map[string]string{"filename": "path/to/file"},
+			input:  "${filename##*/}",
+			output: "file",
+		},
+		{
+			params: map[string]string{"filename": "/path/to/file"},
+			input:  "${filename##*/}",
+			output: "file",
+		},
+		// delete shortest match suffix
+		{
+			params: map[string]string{"filename": "bash.string.txt"},
+			input:  "${filename%.*}",
+			output: "bash.string",
+		},
+		// delete longest match suffix
+		{
+			params: map[string]string{"filename": "bash.string.txt"},
+			input:  "${filename%%.*}",
+			output: "bash",
+		},
+
+		// nested parameters
+		{
+			params: map[string]string{"var01": "abcdEFGH28ij"},
+			input:  "${var=${var01^^}}",
+			output: "ABCDEFGH28IJ",
+		},
+		// escaped
+		{
+			params: map[string]string{"var01": "abcdEFGH28ij"},
+			input:  "$${var01}",
+			output: "${var01}",
+		},
+		{
+			params: map[string]string{"var01": "abcdEFGH28ij"},
+			input:  "some text ${var01}$${var$${var01}$var01${var01}",
+			output: "some text abcdEFGH28ij${var${var01}$var01abcdEFGH28ij",
+		},
+		{
+			params: map[string]string{"default_var": "foo"},
+			input:  "something $${var=${default_var}}",
+			output: "something ${var=foo}",
+		},
+		// some common escaping use cases
+		{
+			params: map[string]string{"stringZ": "foo/bar"},
+			input:  `${stringZ/\//-}`,
+			output: "foo-bar",
+		},
+		{
+			params: map[string]string{"stringZ": "foo/bar/baz"},
+			input:  `${stringZ//\//-}`,
+			output: "foo-bar-baz",
+		},
+		// escape outside of expansion shouldn't be processed
+		{
+			params: map[string]string{"default_var": "foo"},
+			input:  "\\\\something ${var=${default_var}}",
+			output: "\\\\something foo",
+		},
+		// substitute with a blank string
+		{
+			params: map[string]string{"stringZ": "foo.bar"},
+			input:  `${stringZ/./}`,
+			output: "foobar",
+		},
+	}
+
+	for _, expr := range expressions {
+		t.Run(expr.input, func(t *testing.T) {
+			t.Logf(expr.input)
+			output, err := Eval(expr.input, func(s string) string {
+				return expr.params[s]
+			})
+			if err != nil {
+				t.Errorf("Want %q expanded but got error %q", expr.input, err)
+			}
+
+			if output != expr.output {
+				t.Errorf("Want %q expanded to %q, got %q",
+					expr.input,
+					expr.output,
+					output)
+			}
+		})
+	}
+}