From 0117557b8eabf12d94b9e91044e5ac847e3657ba Mon Sep 17 00:00:00 2001
From: Guido Knips <guido.knips@posteo.de>
Date: Fri, 17 Feb 2023 17:43:00 +0100
Subject: [PATCH] Implement Error trait for FixError

---
 src/gtin12/mod.rs | 19 +++++++++++++++++++
 src/gtin13/mod.rs | 20 +++++++++++++++++++-
 src/gtin14/mod.rs | 19 +++++++++++++++++++
 src/gtin8/mod.rs  | 19 +++++++++++++++++++
 4 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/src/gtin12/mod.rs b/src/gtin12/mod.rs
index bc23997..971aba4 100644
--- a/src/gtin12/mod.rs
+++ b/src/gtin12/mod.rs
@@ -1,5 +1,7 @@
 //! Performs validation and correction of GTIN-12 and UPC-A codes.
 
+use std::error::Error;
+use std::fmt;
 use utils;
 
 /// Errors that make GTIN-12 correction impossible.
@@ -13,6 +15,23 @@ pub enum FixError {
     CheckDigitIncorrect,
 }
 
+impl Error for FixError {}
+
+impl fmt::Display for FixError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            FixError::NonAsciiString => {
+                write!(f, "the provided string contains non-ASCII characters")
+            }
+            FixError::TooLong => write!(f, "the provided code was too long too be valid"),
+            FixError::CheckDigitIncorrect => write!(
+                f,
+                "the calculated check-digit did not match the code's check-digit"
+            ),
+        }
+    }
+}
+
 /// Check that a UPC-A code is valid by confirming that it is made of
 /// exactly 12 digits and that the check-digit is correct.
 ///
diff --git a/src/gtin13/mod.rs b/src/gtin13/mod.rs
index a07ac8a..1866b6e 100644
--- a/src/gtin13/mod.rs
+++ b/src/gtin13/mod.rs
@@ -1,5 +1,7 @@
 //! Performs validation and correction of GTIN-13 and EAN-13 codes.
 
+use std::error::Error;
+use std::fmt;
 use utils;
 
 /// Errors that make GTIN-13 correction impossible.
@@ -13,6 +15,23 @@ pub enum FixError {
     CheckDigitIncorrect,
 }
 
+impl Error for FixError {}
+
+impl fmt::Display for FixError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            FixError::NonAsciiString => {
+                write!(f, "the provided string contains non-ASCII characters")
+            }
+            FixError::TooLong => write!(f, "the provided code was too long too be valid"),
+            FixError::CheckDigitIncorrect => write!(
+                f,
+                "the calculated check-digit did not match the code's check-digit"
+            ),
+        }
+    }
+}
+
 /// Check that a GTIN-13 code is valid by checking the length (should be
 /// exactly 13 digits) and that the check-digit is correct.
 ///
@@ -152,7 +171,6 @@ mod tests {
         assert!(fix("❤").is_err());
     }
 
-
     #[test]
     fn fix_too_long() {
         assert_eq!(fix("00000000000000"), Err(FixError::TooLong));
diff --git a/src/gtin14/mod.rs b/src/gtin14/mod.rs
index 8408742..b2da1bb 100644
--- a/src/gtin14/mod.rs
+++ b/src/gtin14/mod.rs
@@ -1,5 +1,7 @@
 //! Performs validation and correction of GTIN-14 codes.
 
+use std::error::Error;
+use std::fmt;
 use utils;
 
 /// Errors that make GTIN-14 correction impossible.
@@ -13,6 +15,23 @@ pub enum FixError {
     CheckDigitIncorrect,
 }
 
+impl Error for FixError {}
+
+impl fmt::Display for FixError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            FixError::NonAsciiString => {
+                write!(f, "the provided string contains non-ASCII characters")
+            }
+            FixError::TooLong => write!(f, "the provided code was too long too be valid"),
+            FixError::CheckDigitIncorrect => write!(
+                f,
+                "the calculated check-digit did not match the code's check-digit"
+            ),
+        }
+    }
+}
+
 /// Check that a GTIN-14 code is valid by confirming that it is exactly
 /// 14 digits in length and that the check-digit is correct.
 ///
diff --git a/src/gtin8/mod.rs b/src/gtin8/mod.rs
index 8befd31..159405f 100644
--- a/src/gtin8/mod.rs
+++ b/src/gtin8/mod.rs
@@ -1,5 +1,7 @@
 //! Performs validation and correction of GTIN-8 codes.
 
+use std::error::Error;
+use std::fmt;
 use utils;
 
 /// Errors that make GTIN-8 correction impossible.
@@ -13,6 +15,23 @@ pub enum FixError {
     CheckDigitIncorrect,
 }
 
+impl Error for FixError {}
+
+impl fmt::Display for FixError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            FixError::NonAsciiString => {
+                write!(f, "the provided string contains non-ASCII characters")
+            }
+            FixError::TooLong => write!(f, "the provided code was too long too be valid"),
+            FixError::CheckDigitIncorrect => write!(
+                f,
+                "the calculated check-digit did not match the code's check-digit"
+            ),
+        }
+    }
+}
+
 /// Check that a GTIN-8 code is valid by confirming that it is exactly
 /// 8 digits in length and that the check-digit is correct.
 ///