feat: improve error struct (#42)

Author: dsherret

.github/workflows/ci.yml

@@ -30,10 +30,10 @@ jobs:
       run: |
         cargo test --features serde
         cargo test --features preserve_order
-        cargo test --verbose --all-features
+        cargo test --all-features
     - name: Test release
       if: matrix.config.kind == 'test_release'
-      run: cargo test --release --verbose --all-features
+      run: cargo test --release --all-features
 
       # CARGO PUBLISH
     - name: Cargo login
@@ -48,14 +48,14 @@ jobs:
     name: Benchmarks
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Install latest nightly
       uses: actions-rs/toolchain@v1
       with:
         toolchain: nightly
         override: true
     - name: Cache cargo
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: |
           ~/.cargo/registry

.github/workflows/release.yml

@@ -20,11 +20,11 @@ jobs:
 
     steps:
       - name: Clone repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           token: ${{ secrets.GH_DPRINTBOT_PAT }}
 
-      - uses: denoland/setup-deno@v1
+      - uses: denoland/setup-deno@v2
       - uses: dsherret/rust-toolchain-file@v1
 
       - name: Bump version and tag

Cargo.toml

@@ -13,11 +13,13 @@ all-features = true
 [dependencies]
 indexmap = { version = "2.2.6", optional = true }
 serde_json = { version = "1.0", optional = true }
+unicode-width = { version = "0.2.0", optional = true }
 
 [features]
 cst = []
 preserve_order = ["indexmap", "serde_json/preserve_order"]
 serde = ["serde_json"]
+error_unicode_width = ["unicode-width"]
 
 [dev-dependencies]
 pretty_assertions = "1.0.0"

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2020-2021 David Sherret
+Copyright (c) 2020 David Sherret
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -92,3 +92,7 @@ let json_value = parse_to_value(text, &ParseOptions {
   allow_trailing_commas: false,
 })?;
 ```
+
+## Error column number with unicode-width
+
+To to get more accurate display column numbers in error messages, enable the `error_unicode_width` cargo feature, which will pull in and use the [unicode-width](https://crates.io/crates/unicode-width) dependency internally. Otherwise it will use the character count, which isn't as accurate of a number, but will probably be good enough in most cases.

dprint.json

@@ -13,6 +13,7 @@
   ],
   "plugins": [
     "https://plugins.dprint.dev/markdown-0.17.8.wasm",
-    "https://plugins.dprint.dev/exec-0.5.0.json@8d9972eee71fa1590e04873540421f3eda7674d0f1aae3d7c788615e7b7413d0"
+    "https://plugins.dprint.dev/exec-0.5.0.json@8d9972eee71fa1590e04873540421f3eda7674d0f1aae3d7c788615e7b7413d0",
+    "https://plugins.dprint.dev/json-0.19.3.wasm"
   ]
 }

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "1.81.0"
+channel = "1.82.0"
 components = ["clippy", "rustfmt"]

src/errors.rs

@@ -1,52 +1,179 @@
-use std::error::Error;
 use std::fmt;
 
+use crate::ParseStringErrorKind;
+
 use super::common::Range;
 
-/// Error that could occur while parsing or tokenizing.
-#[derive(Debug, PartialEq)]
-pub struct ParseError {
-  /// Start and end position of the error.
-  pub range: Range,
-  /// Error message.
-  pub message: String,
-  /// Message with the range text.
-  display_message: String,
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum ParseErrorKind {
+  CommentsNotAllowed,
+  ExpectedColonAfterObjectKey,
+  ExpectedObjectValue,
+  ExpectedDigit,
+  ExpectedDigitFollowingNegativeSign,
+  ExpectedPlusMinusOrDigitInNumberLiteral,
+  ExpectedStringObjectProperty,
+  MultipleRootJsonValues,
+  String(ParseStringErrorKind),
+  TrailingCommasNotAllowed,
+  UnexpectedCloseBrace,
+  UnexpectedCloseBracket,
+  UnexpectedColon,
+  UnexpectedComma,
+  UnexpectedToken,
+  UnexpectedTokenInObject,
+  UnexpectedWord,
+  UnterminatedArray,
+  UnterminatedCommentBlock,
+  UnterminatedObject,
 }
 
-impl ParseError {
-  pub(crate) fn new(range: Range, message: &str, file_text: &str) -> ParseError {
-    let display_message = get_message_with_range(range, message, file_text);
-    ParseError {
-      message: message.to_string(),
-      range,
-      display_message,
+impl std::fmt::Display for ParseErrorKind {
+  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    use ParseErrorKind::*;
+    match self {
+      CommentsNotAllowed => {
+        write!(f, "Comments are not allowed")
+      }
+      ExpectedColonAfterObjectKey => {
+        write!(f, "Expected colon after the string or word in object property")
+      }
+      ExpectedDigit => {
+        write!(f, "Expected digit")
+      }
+      ExpectedDigitFollowingNegativeSign => {
+        write!(f, "Expected digit following negative sign")
+      }
+      ExpectedPlusMinusOrDigitInNumberLiteral => {
+        write!(f, "Expected plus, minus, or digit in number literal")
+      }
+      ExpectedObjectValue => {
+        write!(f, "Expected value after colon in object property")
+      }
+      ExpectedStringObjectProperty => {
+        write!(f, "Expected string for object property")
+      }
+      MultipleRootJsonValues => {
+        write!(f, "Text cannot contain more than one JSON value")
+      }
+      String(kind) => kind.fmt(f),
+      TrailingCommasNotAllowed => {
+        write!(f, "Trailing commas are not allowed")
+      }
+      UnexpectedCloseBrace => {
+        write!(f, "Unexpected close brace")
+      }
+      UnexpectedCloseBracket => {
+        write!(f, "Unexpected close bracket")
+      }
+      UnexpectedColon => {
+        write!(f, "Unexpected colon")
+      }
+      UnexpectedComma => {
+        write!(f, "Unexpected comma")
+      }
+      UnexpectedWord => {
+        write!(f, "Unexpected word")
+      }
+      UnexpectedToken => {
+        write!(f, "Unexpected token")
+      }
+      UnexpectedTokenInObject => {
+        write!(f, "Unexpected token in object")
+      }
+      UnterminatedArray => {
+        write!(f, "Unterminated array")
+      }
+      UnterminatedCommentBlock => {
+        write!(f, "Unterminated comment block")
+      }
+      UnterminatedObject => {
+        write!(f, "Unterminated object")
+      }
     }
   }
 }
 
-impl fmt::Display for ParseError {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "{}", self.display_message)
+#[derive(Debug, Clone, PartialEq)]
+struct ParseErrorInner {
+  range: Range,
+  line_display: usize,
+  column_display: usize,
+  kind: ParseErrorKind,
+}
+
+/// Error that could occur while parsing or tokenizing.
+#[derive(Debug, Clone, PartialEq)]
+pub struct ParseError(Box<ParseErrorInner>);
+
+impl std::error::Error for ParseError {}
+
+impl ParseError {
+  pub(crate) fn new(range: Range, kind: ParseErrorKind, file_text: &str) -> ParseError {
+    let (line_display, column_display) = get_line_and_column_display(range, file_text);
+    ParseError(Box::new(ParseErrorInner {
+      range,
+      line_display,
+      column_display,
+      kind,
+    }))
+  }
+
+  /// Start and end position of the error.
+  pub fn range(&self) -> Range {
+    self.0.range
+  }
+
+  /// 1-indexed line number the error occurred on.
+  pub fn line_display(&self) -> usize {
+    self.0.line_display
+  }
+
+  /// 1-indexed column number the error occurred on.
+  ///
+  /// Note: Use the `error_unicode_width` feature to get the correct column
+  /// number for Unicode characters on the line, otherwise this is just the
+  /// number of characters by default.
+  pub fn column_display(&self) -> usize {
+    self.0.column_display
+  }
+
+  /// Error message.
+  pub fn kind(&self) -> &ParseErrorKind {
+    &self.0.kind
   }
 }
 
-impl Error for ParseError {
-  fn description(&self) -> &str {
-    &self.display_message
+impl fmt::Display for ParseError {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    let inner = &*self.0;
+    write!(
+      f,
+      "{} on line {} column {}",
+      inner.kind, inner.line_display, inner.column_display
+    )
   }
 }
 
-fn get_message_with_range(range: Range, message: &str, file_text: &str) -> String {
+fn get_line_and_column_display(range: Range, file_text: &str) -> (usize, usize) {
   let mut line_index = 0;
   let mut column_index = 0;
   for c in file_text[..range.start].chars() {
     if c == '\n' {
       line_index += 1;
       column_index = 0;
     } else {
-      column_index += 1;
+      #[cfg(feature = "error_unicode_width")]
+      {
+        if let Some(width) = unicode_width::UnicodeWidthChar::width_cjk(c) {
+          column_index += width;
+        }
+      }
+      #[cfg(not(feature = "error_unicode_width"))]
+      {
+        column_index += 1;
+      }
     }
   }
-  format!("{} on line {} column {}.", message, line_index + 1, column_index + 1,)
+  (line_index + 1, column_index + 1)
 }