simplified function to turn alias into full path to make it testable

evaluator/functions.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"crypto/rand"
 	"encoding/csv"
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"math"
@@ -1574,11 +1575,26 @@ func sourceFn(tok token.Token, env *object.Environment, args ...object.Object) o
 // require("file.abs")
 var history = make(map[string]string)
 
-type StringFn func(string) (string, error)
+var packageAliases map[string]string
+var packageAliasesLoaded bool
 
 func requireFn(tok token.Token, env *object.Environment, args ...object.Object) object.Object {
-	getAlias := Memoize(util.ReadAliasFromFile)
-	a, error := getAlias(args[0].Inspect())
+	if !packageAliasesLoaded {
+		a, err := ioutil.ReadFile("./packages.abs.json")
+
+		// We couldn't open the packages, file, possibly doesn't exists
+		// and the code shouldn't fail
+		if err == nil {
+			// Try to decode the packages file:
+			// if an error occurs we will simply
+			// ignore it
+			json.Unmarshal(a, &packageAliases)
+		}
+
+		packageAliasesLoaded = true
+	}
+
+	a, error := util.UnaliasPath(args[0].Inspect(), packageAliases)
 	if error != nil {
 		return newError(tok, "error resolving '%s': %s\n", args[0].Inspect(), error.Error())
 	}
@@ -1588,17 +1604,6 @@ func requireFn(tok token.Token, env *object.Environment, args ...object.Object)
 	return doSource(tok, e, file, args...)
 }
 
-func Memoize(fn StringFn) StringFn {
-	return func(str string) (string, error) {
-		if res, ok := history[str]; ok {
-			return res, nil
-		}
-		res, err := fn(str)
-		history[str] = res
-		return res, err
-	}
-}
-
 func doSource(tok token.Token, env *object.Environment, fileName string, args ...object.Object) object.Object {
 	err := validateArgs(tok, "source", args, 1, [][]string{{object.STRING_OBJ}})
 	if err != nil {

util/util.go

@@ -1,8 +1,6 @@
 package util
 
 import (
-	"encoding/json"
-	"io/ioutil"
 	"os"
 	"os/user"
 	"path/filepath"
@@ -104,26 +102,9 @@ func UniqueStrings(slice []string) []string {
 	return list
 }
 
-// ReadAliasFromFile translates a path alias
+// UnaliasPath translates a path alias
 // to the full path in the filesystem.
-func ReadAliasFromFile(path string) (string, error) {
-	var packageAlias map[string]string
-	a, err := ioutil.ReadFile("./packages.abs.json")
-
-	// We couldn't open the packages, file, possibly doesn't exists
-	// and the code shouldn't fail
-	if err != nil {
-		return path, nil
-	}
-
-	// Try to decode the packages file:
-	// if an error occurs we will simply
-	// ignore it
-	err = json.Unmarshal(a, &packageAlias)
-	if err != nil {
-		return path, err
-	}
-
+func UnaliasPath(path string, packageAlias map[string]string) (string, error) {
 	// An alias can come in different forms:
 	//  - package
 	//  - package/file.abs