From b9e404063528b93ea60167c6a46a5abe6d72fa0b Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Sat, 14 Mar 2020 23:39:45 +0800
Subject: [PATCH] Deprecate Error::description.

---
 src/error.rs  | 37 ++++++++++---------------------------
 src/result.rs | 14 ++++++--------
 2 files changed, 16 insertions(+), 35 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index e769d993..89d6f370 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -20,18 +20,7 @@ pub enum LexError {
     InputError(String),
 }
 
-impl Error for LexError {
-    fn description(&self) -> &str {
-        match *self {
-            Self::UnexpectedChar(_) => "Unexpected character",
-            Self::UnterminatedString => "Open string is not terminated",
-            Self::MalformedEscapeSequence(_) => "Unexpected values in escape sequence",
-            Self::MalformedNumber(_) => "Unexpected characters in number",
-            Self::MalformedChar(_) => "Char constant not a single character",
-            Self::InputError(_) => "Input error",
-        }
-    }
-}
+impl Error for LexError {}
 
 impl fmt::Display for LexError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -41,7 +30,7 @@ impl fmt::Display for LexError {
             Self::MalformedNumber(s) => write!(f, "Invalid number: '{}'", s),
             Self::MalformedChar(s) => write!(f, "Invalid character: '{}'", s),
             Self::InputError(s) => write!(f, "{}", s),
-            _ => write!(f, "{}", self.description()),
+            Self::UnterminatedString => write!(f, "Open string is not terminated"),
         }
     }
 }
@@ -104,10 +93,8 @@ impl ParseError {
     pub fn position(&self) -> Position {
         self.1
     }
-}
 
-impl Error for ParseError {
-    fn description(&self) -> &str {
+    pub(crate) fn desc(&self) -> &str {
         match self.0 {
             ParseErrorType::BadInput(ref p) => p,
             ParseErrorType::InputPastEndOfFile => "Script is incomplete",
@@ -128,39 +115,35 @@ impl Error for ParseError {
             ParseErrorType::AssignmentToConstant(_) => "Cannot assign to a constant variable."
         }
     }
-
-    fn cause(&self) -> Option<&dyn Error> {
-        None
-    }
 }
 
+impl Error for ParseError {}
+
 impl fmt::Display for ParseError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.0 {
             ParseErrorType::BadInput(ref s)
             | ParseErrorType::MalformedIndexExpr(ref s)
             | ParseErrorType::MalformedCallExpr(ref s) => {
-                write!(f, "{}", if s.is_empty() { self.description() } else { s })?
+                write!(f, "{}", if s.is_empty() { self.desc() } else { s })?
             }
             ParseErrorType::ForbiddenConstantExpr(ref s) => {
                 write!(f, "Expecting a constant to assign to '{}'", s)?
             }
-            ParseErrorType::UnknownOperator(ref s) => write!(f, "{}: '{}'", self.description(), s)?,
+            ParseErrorType::UnknownOperator(ref s) => write!(f, "{}: '{}'", self.desc(), s)?,
             ParseErrorType::FnMissingParams(ref s) => {
                 write!(f, "Expecting parameters for function '{}'", s)?
             }
             ParseErrorType::MissingRightParen(ref s)
             | ParseErrorType::MissingRightBrace(ref s)
-            | ParseErrorType::MissingRightBracket(ref s) => {
-                write!(f, "{} for {}", self.description(), s)?
-            }
+            | ParseErrorType::MissingRightBracket(ref s) => write!(f, "{} for {}", self.desc(), s)?,
             ParseErrorType::AssignmentToConstant(ref s) if s.is_empty() => {
-                write!(f, "{}", self.description())?
+                write!(f, "{}", self.desc())?
             }
             ParseErrorType::AssignmentToConstant(ref s) => {
                 write!(f, "Cannot assign to constant '{}'", s)?
             }
-            _ => write!(f, "{}", self.description())?,
+            _ => write!(f, "{}", self.desc())?,
         }
 
         if !self.1.is_eof() {
diff --git a/src/result.rs b/src/result.rs
index acafecc4..faa8db7c 100644
--- a/src/result.rs
+++ b/src/result.rs
@@ -61,10 +61,10 @@ pub enum EvalAltResult {
     Return(Dynamic, Position),
 }
 
-impl Error for EvalAltResult {
-    fn description(&self) -> &str {
+impl EvalAltResult {
+    pub(crate) fn desc(&self) -> &str {
         match self {
-            Self::ErrorParsing(p) => p.description(),
+            Self::ErrorParsing(p) => p.desc(),
             Self::ErrorFunctionNotFound(_, _) => "Function not found",
             Self::ErrorFunctionArgsMismatch(_, _, _, _) => {
                 "Function call with wrong number of arguments"
@@ -101,15 +101,13 @@ impl Error for EvalAltResult {
             Self::Return(_, _) => "[Not Error] Function returns value",
         }
     }
-
-    fn cause(&self) -> Option<&dyn Error> {
-        None
-    }
 }
 
+impl Error for EvalAltResult {}
+
 impl fmt::Display for EvalAltResult {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let desc = self.description();
+        let desc = self.desc();
 
         match self {
             Self::ErrorFunctionNotFound(s, pos) => write!(f, "{}: '{}' ({})", desc, s, pos),