Add Abs method on Document

document.go

@@ -1,5 +1,6 @@
 package step
 
+import "os"
 import "io"
 import "time"
 import "strings"
@@ -57,22 +58,44 @@ func (this *Document) Environment () *Environment {
 
 // Abs returns an absolute representation of the given path. If the path is an
 // absolute path already, it is returned as-is. If the path is a relative path,
-// it is treated as relative to the current working directory. If the path is an
+// it is treated as relative to the current working directory. If the path is a
-// absolute path beginning with "." or "..", it is treated as relative to this
+// relative path beginning with "." or "..", it is treated as relative to this
 // document. The result is cleaned.
 func (this *Document) Abs (name string) (string, error) {
 	if filepath.IsAbs(name) {
 		return filepath.Clean(name), nil
 	}
 	if strings.HasPrefix(name, ".") {
+		directory := this.dir()
+		return filepath.Abs(filepath.Join(directory, name))
+	}
+	return filepath.Abs(name)
+}
+
+// Rel returns the given path relative to the current working directory. As a
+// special case, any relative path beginning with "." or ".." is treated as
+// being relative to this document before it is made relative to the current
+// working directory. The result is cleaned.
+func (this *Document) Rel (name string) (string, error) {
+	if filepath.IsAbs(name) {
+		cwd, err := os.Getwd()
+		if err != nil { return "", err }
+		return filepath.Rel(cwd, name)
+	}
+	if strings.HasPrefix(name, ".") {
+		directory := this.dir()
+		return filepath.Join(directory, name), nil
+	}
+	return name, nil
+}
+
+func (this *Document) dir () string {
 	directory := this.name
 	ext := filepath.Ext(directory)
 	if ext != "" {
 		directory = filepath.Dir(directory)
 	}
-		return filepath.Abs(filepath.Join(directory, name))
+	return directory
-	}
-	return filepath.Abs(name)
 }
 
 // ExecutionData is data made available to documents as they are being exeucted.

document_test.go

@@ -31,3 +31,29 @@ func TestDocumentAbs (test *testing.T) {
 	test.Log(path5)
 	if path5 != "/something/thing" { test.Fatal("incorrect path") }
 }
+
+func TestDocumentRel (test *testing.T) {
+	document := Document {
+		name: "foo/bar.step",
+	}
+	path1, err := document.Rel("thing.step")
+	if err != nil { test.Fatal(err) }
+	path2, err := document.Rel("thing/other.step")
+	if err != nil { test.Fatal(err) }
+	path3, err := document.Rel("./thing/other.step")
+	if err != nil { test.Fatal(err) }
+	path4, err := document.Rel("../thing/other.step")
+	if err != nil { test.Fatal(err) }
+	path5, err := document.Rel("/something/thing")
+	if err != nil { test.Fatal(err) }
+	test.Log(path1)
+	if path1 != filepath.Join("thing.step") { test.Fatal("incorrect path") }
+	test.Log(path2)
+	if path2 != filepath.Join("thing/other.step") { test.Fatal("incorrect path") }
+	test.Log(path3)
+	if path3 != filepath.Join("foo/thing/other.step") { test.Fatal("incorrect path") }
+	test.Log(path4)
+	if path4 != filepath.Join("thing/other.step") { test.Fatal("incorrect path") }
+	test.Log(path5)
+	if path5 == "/something/thing" { test.Fatal("incorrect path") }
+}