to build or not to build is the question

wit.go

@@ -24,6 +24,57 @@ func (m *Machine) IsInstalled(name string) bool {
 	return false
 }
 
+func (m *Machine) FindInstalledByName(name string) *Package {
+	loop := m.Packages.SortByName()
+	for loop.Scan() {
+		p := loop.Package()
+		if name == p.Name {
+			// log.Info("package installed:", p.Name, p.Version, p.PkgName)
+			return p
+		}
+	}
+
+	// log.Info("package not-installed:", name)
+	return nil
+}
+
+// looks to see if any package matches a name and version
+// if version == "", return the first name found
+func (m *Machine) FindVersion(name string, version string) *Package {
+	// first check all installed versions
+	loop := m.Packages.SortByName()
+	for loop.Scan() {
+		p := loop.Package()
+		if name == p.Name {
+			if version == "" {
+				return p
+			} else {
+				if version == p.Version {
+					return p
+				}
+			}
+		}
+	}
+
+	// check all wit packages
+	loop = m.Wit.SortByName()
+	for loop.Scan() {
+		p := loop.Package()
+		if name == p.Name {
+			if version == "" {
+				return p
+			} else {
+				if version == p.Version {
+					return p
+				}
+			}
+		}
+	}
+
+	// log.Info("package not-installed:", name)
+	return nil
+}
+
 // read the package list file from mirrors.wit.com
 func (m *Machine) InitWit() error {
 	if m.Wit == nil {