Fix #12 Provide a way to get error message when parsing fails

Author: ngocdaothanh

CHANGELOG

@@ -1,3 +1,8 @@
+1.6
+
+* Provide a way to get error message when parsing fails
+  https://github.com/xitrum-framework/scaposer/issues/12
+
 1.5:
 
 * Use the original string when it's still not translated

README.rst

@@ -21,17 +21,18 @@ See `Scaladoc <http://xitrum-framework.github.io/scaposer/>`_.
   msgstr "Bonjour"
   """
 
-  val poo = scaposer.Parser.parsePo(string)  // => An Option[scaposer.Po] (None on failure)
+  val poe = scaposer.Parser.parsePo(string)
+  // => An Either, Left((error msg, error position)) on failure, or Right(scaposer.Po) on success
 
 Use ``t`` methods to get the translations:
 
 ::
 
-  val po = poo.get // => A scaposer.Po
-  po.t("Hello")    // => "Bonjour"
+  val po = poe.right.get // => A scaposer.Po
+  po.t("Hello")          // => "Bonjour"
 
 If there's no translation, or the translation is an empty string (not translated yet),
-the input is returned:
+the original input is returned:
 
 ::
 
@@ -53,7 +54,7 @@ Context
   msgstr "Salut"
   """
 
-  val po = Parser.parsePo(string).get
+  val po = Parser.parsePo(string).right.get
   po.t("Casual", "Hello")  // => "Salut"
 
 If there's no translation for the context, the translation without context is tried:
@@ -87,7 +88,7 @@ It just removes spaces in the expression and performs string comparison. See
   msgstr[1] "J'ai %d pommes"
   """
 
-  val po = Parser.parsePo(string).get
+  val po = Parser.parsePo(string).right.get
   po.t("I have one apple", "I have %d apples", 1)
   po.t("I have one apple", "I have %d apples", 2)
   po.t("A context", "I have one apple", "I have %d apples", 3)
@@ -113,6 +114,6 @@ build.sbt example:
 
 ::
 
-  libraryDependencies += "tv.cntt" %% "scaposer" % "1.5"
+  libraryDependencies += "tv.cntt" %% "scaposer" % "1.6"
 
-Scaposer is used in `Xitrum <https://github.com/xitrum-framework/xitrum>`_.
+Scaposer is used in `Xitrum web framework <https://github.com/xitrum-framework/xitrum>`_.

build.sbt

@@ -1,12 +1,9 @@
-organization       := "tv.cntt"
+organization := "tv.cntt"
+name         := "scaposer"
+version      := "1.7-SNAPSHOT"
 
-name               := "scaposer"
-
-version            := "1.6-SNAPSHOT"
-
-scalaVersion       := "2.11.4"
-
-crossScalaVersions := Seq("2.11.4", "2.10.4")
+scalaVersion       := "2.11.6"
+crossScalaVersions := Seq("2.11.6", "2.10.5")
 
 scalacOptions ++= Seq("-deprecation", "-feature", "-unchecked")
 
@@ -16,11 +13,11 @@ scalacOptions ++= Seq("-deprecation", "-feature", "-unchecked")
 // java.lang.UnsupportedClassVersionError: Unsupported major.minor version 51.0
 javacOptions ++= Seq("-source", "1.6", "-target", "1.6")
 
-// Scala 2.11 does not include scala.util.parsing.combinator
+// Scala 2.11 core does not include scala.util.parsing.combinator
 libraryDependencies := {
   CrossVersion.partialVersion(scalaVersion.value) match {
     case Some((2, scalaMajor)) if scalaMajor >= 11 =>
-      libraryDependencies.value :+ "org.scala-lang.modules" %% "scala-parser-combinators" % "1.0.2"
+      libraryDependencies.value :+ "org.scala-lang.modules" %% "scala-parser-combinators" % "1.0.4"
     case _ =>
       libraryDependencies.value
   }

project/build.properties

@@ -1 +1 @@
-sbt.version=0.13.7
+sbt.version=0.13.8

project/plugins.sbt

@@ -1,5 +1,2 @@
 // Run sbt eclipse to create Eclipse project file
-addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.5.0")
-
-// Run sbt gen-idea to create IntelliJ project file
-addSbtPlugin("com.github.mpeltonen" % "sbt-idea" % "1.6.0")
+addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "4.0.0")

src/main/scala/scaposer/Parser.scala

@@ -1,9 +1,22 @@
 package scaposer
 
 import scala.util.parsing.combinator.JavaTokenParsers
+import scala.util.parsing.input.Position
+
+// We only want to expose parsePo method.
+object Parser {
+  private val parser = new Parser
+
+  /**
+   * Returns an `Either`,
+   * `Left((error msg, error position))` on failure,
+   * or `Right(scaposer.Po)` on success.
+   */
+  def parsePo(po: String) = parser.parsePo(po)
+}
 
 /** See http://www.gnu.org/software/hello/manual/gettext/PO-Files.html */
-object Parser extends JavaTokenParsers {
+private class Parser extends JavaTokenParsers {
   private def mergeStrs(quoteds: List[String]): String = {
     // Removes the first and last quote (") character of strings
     // and concats them
@@ -73,19 +86,25 @@ object Parser extends JavaTokenParsers {
 
   private def exp = rep(singular | plural)
 
-  def parsePo(po: String): Option[Po] = {
-    val parseRet = parseAll(exp, po)
-    if (parseRet.successful) {
-      val translations = parseRet.get
-      val body         = translations.foldLeft(
-        Map.empty[(Option[String], String), Seq[String]]
-      ) { (acc, t) =>
-        val item = (t.ctxo, t.singular) -> t.strs
-        acc + item
-      }
-      Some(new Po(body))
-    } else {
-      None
+  /**
+   * Returns an `Either`,
+   * `Left((error msg, error position))` on failure,
+   * or `Right(scaposer.Po)` on success.
+   */
+  def parsePo(po: String): Either[(String, Position), Po] = {
+    parseAll(exp, po) match {
+      case NoSuccess(msg, next) =>
+        val errorPos = next.pos
+        Left((msg, errorPos))
+
+      case Success(translations, _) =>
+        val body = translations.foldLeft(
+          Map.empty[(Option[String], String), Seq[String]]
+        ) { (acc, t) =>
+          val item = (t.ctxo, t.singular) -> t.strs
+          acc + item
+        }
+        Right(new Po(body))
     }
   }
 }

src/main/scala/scaposer/Po.scala

@@ -1,8 +1,7 @@
 package scaposer
 
 /**
- * body is a map of (ctxo, singular) -> strs
- * See also class Translation.
+ * `body` is a map of `(ctxo, singular) -> strs`, see class [[Translation]].
  */
 class Po(val body: Map[(Option[String], String), Seq[String]]) {
   def ++(other: Po): Po = {
@@ -35,7 +34,7 @@ class Po(val body: Map[(Option[String], String), Seq[String]]) {
     val buffer = new StringBuilder
     buffer.append("\n")
     body.foreach { case ((ctxo, singular), strs) =>
-      if (!ctxo.isEmpty) {
+      if (ctxo.isDefined) {
         buffer.append(ctxo.get)
         buffer.append("\n")
       }
@@ -44,7 +43,7 @@ class Po(val body: Map[(Option[String], String), Seq[String]]) {
       buffer.append("\n")
 
       if (strs.size == 1) {
-        buffer.append(strs(0))
+        buffer.append(strs.head)
         buffer.append("\n")
       } else {
         strs.zipWithIndex.foreach { case (str, index) =>
@@ -65,7 +64,7 @@ class Po(val body: Map[(Option[String], String), Seq[String]]) {
     body.get((ctxo, singular)) match {
       case Some(strs) =>
         // Newly created .pot/.po files have keys but the values are all empty
-        val str = strs(0)
+        val str = strs.head
         if (str.isEmpty) singular else str
 
       case None =>
@@ -104,7 +103,7 @@ class Po(val body: Map[(Option[String], String), Seq[String]]) {
       case None => None
 
       case Some(strs) =>
-        val header = strs(0)
+        val header = strs.head
         header.lines.find(_.startsWith("Plural-Forms")) match {
           case None => None
 

src/main/scala/scaposer/Translation.scala

@@ -1,9 +1,8 @@
 package scaposer
 
-// msgid_plural in po file is for translators. We do not need to store it here
-// because it is available in the translation methods of class Po.
-class Translation(
-  val ctxo:     Option[String],
-  val singular: String,
-  val strs:     Seq[String]
-)
+/**
+ * Represents a translation item.
+ * `msgid_plural` in po file is for translators. We do not need to store it here
+ * because it is available in the translation methods of class [[Po]].
+ */
+case class Translation(ctxo: Option[String], singular: String, strs: Seq[String])

src/test/scala/scaposer/ParserSpec.scala

@@ -10,8 +10,8 @@ class ParserSpec extends Specification {
     """.stripMargin
 
   "PO singular string" should {
-    "be some" in {
-      Parser.parsePo(strPoSimple) must beSome
+    "be Right" in {
+      Parser.parsePo(strPoSimple) must beRight
     }
   }
 
@@ -24,8 +24,8 @@ class ParserSpec extends Specification {
     """.stripMargin
 
   "PO singular string with \"" should {
-    "not be none" in {
-      Parser.parsePo(strPoWithSlash) must not beNone
+    "be Right" in {
+      Parser.parsePo(strPoWithSlash) must beRight
     }
   }
 
@@ -38,8 +38,8 @@ class ParserSpec extends Specification {
     """.stripMargin
 
   "PO singular string with \" with no doublequotes at the end" should {
-    "be none" in {
-      Parser.parsePo(strPoWithError) must beNone
+    "be Left" in {
+      Parser.parsePo(strPoWithError) must beLeft
     }
   }
 
@@ -55,8 +55,8 @@ class ParserSpec extends Specification {
     """.stripMargin
 
   "PO string with tabulation character" should {
-    "not be none" in {
-      Parser.parsePo(strPoWithWhiteSpaces) must not beNone
+    "be Right" in {
+      Parser.parsePo(strPoWithWhiteSpaces) must beRight
     }
   }
 }

src/test/scala/scaposer/PoSpec.scala

@@ -14,7 +14,7 @@ class PoSpec extends Specification {
         |msgstr[0] "Yksi ankanpoikanen"
         |msgstr[1] "$n ankanpoikasta"
       """.stripMargin
-    ).get
+    ).right.get
 
     "work" in {
       po.t("One duckling", "$n ducklings", 2) must equalTo ("$n ankanpoikasta")
@@ -24,7 +24,7 @@ class PoSpec extends Specification {
   }
 
   "Missing translations" should {
-    val po = Parser.parsePo("").get
+    val po = Parser.parsePo("").right.get
 
     "be pluralized with the n != 1 rule" in {
       po.t("One monkey", "$n monkeys", 2) must equalTo ("$n monkeys")
@@ -39,7 +39,7 @@ class PoSpec extends Specification {
         |msgid "Could not login."
         |msgstr ""
       """.stripMargin
-    ).get
+    ).right.get
 
     "use msgid instead of the meaningless empty msgstr" in {
       po.t("Could not login.") must equalTo ("Could not login.")