refact: make FialedParserResult to implement std::Error:Error.

src/combinators.rs

@@ -219,7 +219,7 @@ where
     PSeparator: Parser<'a, TToken, TSeparator, TContext>,
 {
     separate_by1(parser, separator).next(|r| match r {
-        Err((input, _)) => Ok((input, vec![])),
+        Err(r) => Ok((r.input(), vec![])),
         r => r,
     })
 }
@@ -274,7 +274,7 @@ where
     PSeparator: Parser<'a, TToken, TSeparator, TContext>,
 {
     separate_or_end_by1(parser, separator).next(|r| match r {
-        Err((i, _)) => Ok((i, vec![])),
+        Err(r) => Ok((r.input(), vec![])),
         r => r,
     })
 }

src/combinators/many_parsers.rs

@@ -136,9 +136,9 @@ where
                 input = i;
                 result.push(r);
             } else {
-                return Err((
+                return Err(FailedParserResult::new_with_str(
                     input,
-                    FailedParserResult::new("End with other elements.".to_owned()),
+                    "End with other elements.",
                 ));
             }
         }
@@ -174,9 +174,9 @@ where
                 result.push(r);
                 input = i;
             } else {
-                return Err((
+                return Err(FailedParserResult::new_with_str(
                     input,
-                    FailedParserResult::new("End with other elements.".to_owned()),
+                    "End with other elements.",
                 ));
             }
         }

src/parser.rs

@@ -10,33 +10,51 @@ use crate::parser::primitive_parsers::{
     TakeParser,
 };
 use std::cell::RefCell;
+use std::error::Error;
 use std::fmt::{Debug, Display, Formatter};
 use std::marker::PhantomData;
 use std::rc::Rc;
 
 #[derive(Debug)]
-pub struct FailedParserResult {
+pub struct FailedParserResult<'a, TToken: Debug> {
+    input: &'a [TToken],
     message: String,
 }
 
-impl FailedParserResult {
-    pub fn new(message: String) -> Self {
-        Self { message }
+impl<'a, TToken: Debug> FailedParserResult<'a, TToken> {
+    pub fn new(input: &'a [TToken], message: String) -> Self {
+        Self { input, message }
+    }
+
+    pub fn new_with_str(input: &'a [TToken], message: &'static str) -> Self {
+        Self {
+            input,
+            message: message.to_owned(),
+        }
     }
 
     pub fn message(&self) -> &str {
         self.message.as_str()
     }
-}
 
-impl Display for FailedParserResult {
-    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        write!(f, "Parse failed: {}.", self.message)
+    pub fn input(&self) -> &'a [TToken] {
+        self.input
     }
 }
 
-pub type ParserResult<'a, TToken, T> =
-    Result<(&'a [TToken], T), (&'a [TToken], FailedParserResult)>;
+impl<'a, TToken: Debug> Error for FailedParserResult<'a, TToken> {}
+
+impl<'a, TToken: Debug> Display for FailedParserResult<'a, TToken> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "Parse failed: {}, the input is '{:?}'.",
+            self.message, self.input
+        )
+    }
+}
+
+pub type ParserResult<'a, TToken, T> = Result<(&'a [TToken], T), FailedParserResult<'a, TToken>>;
 
 pub struct ParserContext<TToken, TContext>
 where

src/parser/modified_parsers.rs

@@ -121,11 +121,9 @@ where
         let (input, _) = self.parser.parse(context, input)?;
 
         if origin_input.is_empty() {
-            return Err((
+            return Err(FailedParserResult::new_with_str(
                 input,
-                FailedParserResult::new(
-                    "Empty input, the 'literal' parser cann't get length of elememt.".to_owned(),
-                ),
+                "Empty input, the 'literal' parser cann't get length of elememt.",
             ));
         }
 
@@ -156,11 +154,9 @@ where
         let (input, _) = self.parser.parse(context, input)?;
 
         if origin_input.is_empty() {
-            return Err((
+            return Err(FailedParserResult::new_with_str(
                 input,
-                FailedParserResult::new(
-                    "Empty input, the 'literal' parser cann't get length of elememt.".to_owned(),
-                ),
+                "Empty input, the 'literal' parser cann't get length of elememt.",
             ));
         }
 
@@ -212,11 +208,11 @@ where
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, TResult> {
         match self.parser.parse(context, input) {
-            Ok((input, _)) => Err((
+            Ok(_) => Err(FailedParserResult::new_with_str(
                 input,
-                FailedParserResult::new("Reverse failed succeeded.".to_owned()),
+                "Reverse successful parser.",
             )),
-            Err((input, _)) => Ok((input, self.result.clone())),
+            Err(_) => Ok((input, self.result.clone())),
         }
     }
 }
@@ -269,7 +265,7 @@ mod test {
             let (input, result) = satisfy(|c: &char| c.is_numeric()).parse(context, input)?;
 
             match result.to_digit(10) {
-                None => Err((input, FailedParserResult::new("What?".to_string()))),
+                None => Err(FailedParserResult::new_with_str(input, "What?")),
                 Some(r) => Ok((input, Number(r as i32))),
             }
         }
@@ -300,7 +296,7 @@ mod test {
             satisfy(|c: &char| c.is_numeric())
                 .next(|r| match r {
                     Ok((input, result)) => match result.to_digit(10) {
-                        None => Err((input, FailedParserResult::new("What?".to_string()))),
+                        None => Err(FailedParserResult::new_with_str(input, "What?")),
                         Some(r) => Ok((input, Number(r as i32))),
                     },
                     Err(r) => Err(r),

src/parser/primitive_parsers.rs

@@ -35,9 +35,9 @@ where
         _: Rc<RefCell<ParserContext<TToken, TContext>>>,
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, T> {
-        Err((
+        Err(FailedParserResult::new_with_str(
             input,
-            FailedParserResult::new("Default failed parser.".to_owned()),
+            "Default failed parser.",
         ))
     }
 }
@@ -56,7 +56,7 @@ where
         _: Rc<RefCell<ParserContext<TToken, TContext>>>,
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, T> {
-        Err((input, FailedParserResult::new(self.message.clone())))
+        Err(FailedParserResult::new(input, self.message.clone()))
     }
 }
 
@@ -75,16 +75,13 @@ where
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, TToken> {
         if input.is_empty() {
-            return Err((input, FailedParserResult::new("Input is empty.".to_owned())));
+            return Err(FailedParserResult::new_with_str(input, "Input is empty"));
         }
 
         if (self.predicate)(&input[0]) {
             Ok((&input[1..], input[0].clone()))
         } else {
-            Err((
-                input,
-                FailedParserResult::new("Predicate failed.".to_owned()),
-            ))
+            Err(FailedParserResult::new_with_str(input, "Predicate failed."))
         }
     }
 }
@@ -101,7 +98,7 @@ where
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, TToken> {
         if input.is_empty() {
-            Err((input, FailedParserResult::new("Input is empty.".to_owned())))
+            Err(FailedParserResult::new_with_str(input, "Input is empty"))
         } else {
             Ok((&input[1..], input[0].clone()))
         }
@@ -122,12 +119,12 @@ where
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, Vec<TToken>> {
         if input.len() < self.count {
-            Err((
+            Err(FailedParserResult::new(
                 input,
-                FailedParserResult::new(format!(
+                format!(
                     "The input doesn't contain enough {} elemements.",
                     self.count
-                )),
+                ),
             ))
         } else {
             Ok((
@@ -152,12 +149,12 @@ where
         input: &'a [TToken],
     ) -> ParserResult<'a, TToken, ()> {
         if input.len() < self.count {
-            Err((
+            Err(FailedParserResult::new(
                 input,
-                FailedParserResult::new(format!(
+                format!(
                     "The input doesn't contain enough {} elemements.",
                     self.count
-                )),
+                ),
             ))
         } else {
             Ok((&input[self.count..], ()))

tests/file_lexical_parser_tests.rs

@@ -78,7 +78,7 @@ fn file_lexical_parser_test() -> anyhow::Result<()> {
         let context = ParserContext::new_with_str(source_file.content.as_str(), ());
         let borrowed_context = context.borrow();
         let (_, zero_tokens) = zero_lexical_parser(context.clone(), borrowed_context.input_slice())
-            .or_else(|e| Err(anyhow!("{}", e.1)))?;
+            .or_else(|e| Err(anyhow!("{}", e)))?;
 
         assert_eq!(nom_tokens.len(), zero_tokens.len());