fix: work-around incomplete variable interpolation

common/nix_candidate_source.go

@@ -6,8 +6,6 @@ import (
 	"runtime"
 	"strings"
 
-	"go.spiff.io/expand"
-
 	g "github.com/zyedidia/generic"
 	"github.com/zyedidia/generic/hashset"
 )
@@ -115,10 +113,8 @@ func (s *NixCandidateSource) crawlPathLists() {
 
 // input is some path definition
 func (s *NixCandidateSource) harvestPaths(input string) []string {
-	input = fixHomeExpansion(input)
-	input = strings.TrimSpace(input)
-	input = strings.Trim(input, fmt.Sprintf("%v\"'", os.PathListSeparator))
-	inputExpanded := expand.Expand(input, func(key string) (value string, ok bool) {
+
+	inputExpanded := CustomExpandVariables(input, func(key string) (value string, ok bool) {
 		switch key {
 		// do not expand the desired variable itself
 		case s.key:

common/os_filesystem.go

@@ -3,7 +3,6 @@ package common
 import (
 	"os"
 	"path/filepath"
-	"strings"
 
 	"github.com/mitchellh/go-homedir"
 	"go.spiff.io/expand"
@@ -13,7 +12,7 @@ type OsFilesystem struct{}
 
 func (*OsFilesystem) GetAbsolutePath(path string) string {
 	// homedir is assumed to work correctly
-	path = fixHomeExpansion(path)
+	path = ConvertSimpleVarsToBraces(path)
 	expandedPath, err := homedir.Expand(path)
 	if err == nil {
 		path = expandedPath
@@ -25,12 +24,6 @@ func (*OsFilesystem) GetAbsolutePath(path string) string {
 	return expand.Expand(path, os.LookupEnv)
 }
 
-func fixHomeExpansion(path string) string {
-	path = strings.ReplaceAll(path, "$HOME/", "~/")
-	path = strings.ReplaceAll(path, "${HOME}/", "~/")
-	return path
-}
-
 // returns (exists, isDir)
 func (f *OsFilesystem) PathStatus(path string) (bool, bool) {
 	path = f.GetAbsolutePath(path)

common/variable_expander.go

@@ -0,0 +1,25 @@
+package common
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+
+	"go.spiff.io/expand"
+)
+
+func CustomExpandVariables(input string, fn func(key string) (value string, ok bool)) string {
+	input = ConvertSimpleVarsToBraces(input)
+	input = strings.TrimSpace(input)
+	input = strings.Trim(input, fmt.Sprintf("%v\"'", os.PathListSeparator))
+	return expand.Expand(input, fn)
+}
+
+func ConvertSimpleVarsToBraces(input string) string {
+	r := regexp.MustCompile(`\$([0-9a-zA-Z_]+)`)
+	return r.ReplaceAllStringFunc(input, func(m string) string {
+		parts := r.FindStringSubmatch(m)
+		return fmt.Sprintf(`${%s}`, parts[1])
+	})
+}

common/variable_expander_test.go

@@ -0,0 +1,24 @@
+package common
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_expanding_with_custom_callback(t *testing.T) {
+	input := "${VAR1}/$VAR2/bin"
+
+	res := CustomExpandVariables(input, func(key string) (string, bool) {
+		switch key {
+		case "VAR1":
+			return "/var1", true
+		case "VAR2":
+			return "var2", true
+		default:
+			return os.LookupEnv(key)
+		}
+	})
+	assert.Equal(t, "/var1/var2/bin", res)
+}