From 20a5b0adf32b81838c4a0a6ef8188d4c78e3f961 Mon Sep 17 00:00:00 2001
From: Eric Scouten <git@scouten.me>
Date: Sun, 10 Dec 2023 18:31:18 -0800
Subject: [PATCH] Add Error and ParseResult types (#7)

---
 Cargo.toml   |  1 +
 src/error.rs | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs   |  3 +++
 3 files changed, 53 insertions(+)
 create mode 100644 src/error.rs

diff --git a/Cargo.toml b/Cargo.toml
index b6287b5..64ca685 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,3 +11,4 @@ rust-version = "1.72.0"
 
 [dependencies]
 nom = "7.1"
+thiserror = "1.0.50"
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..259f5b0
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,49 @@
+use nom::{
+    error::{ErrorKind, FromExternalError, ParseError},
+    IResult,
+};
+
+/// The error type for AsciiDoc parsing operations.
+#[non_exhaustive]
+#[derive(Clone, Debug, thiserror::Error, PartialEq, Eq)]
+pub enum Error {
+    /// AsciiDoc data was incomplete.
+    #[error("Incomplete data, missing: {0:?}")]
+    Incomplete(nom::Needed),
+
+    /// Error from nom parsing framework.
+    #[error("nom error: {0:?}")]
+    NomError(ErrorKind),
+}
+
+impl<'a> ParseError<&'a str> for Error {
+    fn from_error_kind(_input: &'a str, kind: ErrorKind) -> Self {
+        Error::NomError(kind)
+    }
+
+    fn append(_input: &'a str, kind: ErrorKind, _other: Self) -> Self {
+        Error::NomError(kind)
+    }
+}
+
+impl From<nom::Err<Error>> for Error {
+    fn from(e: nom::Err<Error>) -> Self {
+        match e {
+            nom::Err::Incomplete(n) => Self::Incomplete(n),
+            nom::Err::Error(e) | nom::Err::Failure(e) => e,
+        }
+    }
+}
+
+impl<I, E> FromExternalError<I, E> for Error {
+    fn from_external_error(_input: I, kind: ErrorKind, _e: E) -> Error {
+        Error::NomError(kind)
+    }
+}
+
+/// Holds the result of AsciiDoc parsing functions.
+///
+/// Note that this type is also a [`Result`], so the usual functions (`map`,
+/// `unwrap`, etc.) are available.
+#[allow(dead_code)] // TEMPORARY
+pub type ParseResult<'a, T, E = Error> = IResult<&'a str, T, E>;
diff --git a/src/lib.rs b/src/lib.rs
index 069f003..e701ecb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,9 @@
 #![deny(warnings)]
 #![doc = include_str!("../README.md")]
 
+mod error;
+pub use error::{Error, ParseResult};
+
 pub(crate) mod primitives;
 pub mod strings;