Add custom error with variants to parser module (#50)

* Add custom error with variants to `parser` module

* Replace `unwrap_or` with proper Result handling

* Fix clippy warning

Closes #38

Cargo.toml

@@ -16,6 +16,7 @@ serde_json = "1.0"
 regex = "1"
 pest = "2.0"
 pest_derive = "2.0"
+thiserror = "1.0.50"
 
 [dev-dependencies]
 lazy_static = "1.0"

src/parser/errors.rs

@@ -0,0 +1,18 @@
+use pest::iterators::Pairs;
+use thiserror::Error;
+
+use super::parser::Rule;
+
+#[derive(Error, Debug)]
+pub enum JsonPathParserError<'a> {
+    #[error("Failed to parse rule: {0}")]
+    PestError(#[from] pest::error::Error<Rule>),
+    #[error("Failed to parse JSON: {0}")]
+    JsonParsingError(#[from] serde_json::Error),
+    #[error("{0}")]
+    ParserError(String),
+    #[error("Unexpected rule {0:?} when trying to parse logic atom: {1:?}")]
+    UnexpectedRuleLogicError(Rule, Pairs<'a, Rule>),
+    #[error("Unexpected `none` when trying to parse logic atom: {0:?}")]
+    UnexpectedNoneLogicError(Pairs<'a, Rule>),
+}

src/parser/mod.rs

@@ -1,7 +1,9 @@
 //! The parser for the jsonpath.
 //! The module grammar denotes the structure of the parsing grammar
 
+pub mod errors;
 mod macros;
 pub mod model;
 #[allow(clippy::module_inception)]
+#[allow(clippy::result_large_err)]
 pub mod parser;