1 use crate::util::{
2     primitives::{PatternID, SmallIndex},
3     search::MatchKind,
4 };
5 
6 /// An error that occurred during the construction of an Aho-Corasick
7 /// automaton.
8 ///
9 /// Build errors occur when some kind of limit has been exceeded, either in the
10 /// number of states, the number of patterns of the length of a pattern. These
11 /// limits aren't part of the public API, but they should generally be large
12 /// enough to handle most use cases.
13 ///
14 /// When the `std` feature is enabled, this implements the `std::error::Error`
15 /// trait.
16 #[derive(Clone, Debug)]
17 pub struct BuildError {
18     kind: ErrorKind,
19 }
20 
21 /// The kind of error that occurred.
22 #[derive(Clone, Debug)]
23 enum ErrorKind {
24     /// An error that occurs when allocating a new state would result in an
25     /// identifier that exceeds the capacity of a `StateID`.
26     StateIDOverflow {
27         /// The maximum possible id.
28         max: u64,
29         /// The maximum ID requested.
30         requested_max: u64,
31     },
32     /// An error that occurs when adding a pattern to an Aho-Corasick
33     /// automaton would result in an identifier that exceeds the capacity of a
34     /// `PatternID`.
35     PatternIDOverflow {
36         /// The maximum possible id.
37         max: u64,
38         /// The maximum ID requested.
39         requested_max: u64,
40     },
41     /// Occurs when a pattern string is given to the Aho-Corasick constructor
42     /// that is too long.
43     PatternTooLong {
44         /// The ID of the pattern that was too long.
45         pattern: PatternID,
46         /// The length that was too long.
47         len: usize,
48     },
49 }
50 
51 impl BuildError {
state_id_overflow( max: u64, requested_max: u64, ) -> BuildError52     pub(crate) fn state_id_overflow(
53         max: u64,
54         requested_max: u64,
55     ) -> BuildError {
56         BuildError { kind: ErrorKind::StateIDOverflow { max, requested_max } }
57     }
58 
pattern_id_overflow( max: u64, requested_max: u64, ) -> BuildError59     pub(crate) fn pattern_id_overflow(
60         max: u64,
61         requested_max: u64,
62     ) -> BuildError {
63         BuildError {
64             kind: ErrorKind::PatternIDOverflow { max, requested_max },
65         }
66     }
67 
pattern_too_long( pattern: PatternID, len: usize, ) -> BuildError68     pub(crate) fn pattern_too_long(
69         pattern: PatternID,
70         len: usize,
71     ) -> BuildError {
72         BuildError { kind: ErrorKind::PatternTooLong { pattern, len } }
73     }
74 }
75 
76 #[cfg(feature = "std")]
77 impl std::error::Error for BuildError {}
78 
79 impl core::fmt::Display for BuildError {
fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result80     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
81         match self.kind {
82             ErrorKind::StateIDOverflow { max, requested_max } => {
83                 write!(
84                     f,
85                     "state identifier overflow: failed to create state ID \
86                      from {}, which exceeds the max of {}",
87                     requested_max, max,
88                 )
89             }
90             ErrorKind::PatternIDOverflow { max, requested_max } => {
91                 write!(
92                     f,
93                     "pattern identifier overflow: failed to create pattern ID \
94                      from {}, which exceeds the max of {}",
95                     requested_max, max,
96                 )
97             }
98             ErrorKind::PatternTooLong { pattern, len } => {
99                 write!(
100                     f,
101                     "pattern {} with length {} exceeds \
102                      the maximum pattern length of {}",
103                     pattern.as_usize(),
104                     len,
105                     SmallIndex::MAX.as_usize(),
106                 )
107             }
108         }
109     }
110 }
111 
112 /// An error that occurred during an Aho-Corasick search.
113 ///
114 /// An error that occurs during a search is limited to some kind of
115 /// misconfiguration that resulted in an illegal call. Stated differently,
116 /// whether an error occurs is not dependent on the specific bytes in the
117 /// haystack.
118 ///
119 /// Examples of misconfiguration:
120 ///
121 /// * Executing a stream or overlapping search on a searcher that was built was
122 /// something other than [`MatchKind::Standard`](crate::MatchKind::Standard)
123 /// semantics.
124 /// * Requested an anchored or an unanchored search on a searcher that doesn't
125 /// support unanchored or anchored searches, respectively.
126 ///
127 /// When the `std` feature is enabled, this implements the `std::error::Error`
128 /// trait.
129 #[derive(Clone, Debug, Eq, PartialEq)]
130 pub struct MatchError(alloc::boxed::Box<MatchErrorKind>);
131 
132 impl MatchError {
133     /// Create a new error value with the given kind.
134     ///
135     /// This is a more verbose version of the kind-specific constructors, e.g.,
136     /// `MatchError::unsupported_stream`.
new(kind: MatchErrorKind) -> MatchError137     pub fn new(kind: MatchErrorKind) -> MatchError {
138         MatchError(alloc::boxed::Box::new(kind))
139     }
140 
141     /// Returns a reference to the underlying error kind.
kind(&self) -> &MatchErrorKind142     pub fn kind(&self) -> &MatchErrorKind {
143         &self.0
144     }
145 
146     /// Create a new "invalid anchored search" error. This occurs when the
147     /// caller requests an anchored search but where anchored searches aren't
148     /// supported.
149     ///
150     /// This is the same as calling `MatchError::new` with a
151     /// [`MatchErrorKind::InvalidInputAnchored`] kind.
invalid_input_anchored() -> MatchError152     pub fn invalid_input_anchored() -> MatchError {
153         MatchError::new(MatchErrorKind::InvalidInputAnchored)
154     }
155 
156     /// Create a new "invalid unanchored search" error. This occurs when the
157     /// caller requests an unanchored search but where unanchored searches
158     /// aren't supported.
159     ///
160     /// This is the same as calling `MatchError::new` with a
161     /// [`MatchErrorKind::InvalidInputUnanchored`] kind.
invalid_input_unanchored() -> MatchError162     pub fn invalid_input_unanchored() -> MatchError {
163         MatchError::new(MatchErrorKind::InvalidInputUnanchored)
164     }
165 
166     /// Create a new "unsupported stream search" error. This occurs when the
167     /// caller requests a stream search while using an Aho-Corasick automaton
168     /// with a match kind other than [`MatchKind::Standard`].
169     ///
170     /// The match kind given should be the match kind of the automaton. It
171     /// should never be `MatchKind::Standard`.
unsupported_stream(got: MatchKind) -> MatchError172     pub fn unsupported_stream(got: MatchKind) -> MatchError {
173         MatchError::new(MatchErrorKind::UnsupportedStream { got })
174     }
175 
176     /// Create a new "unsupported overlapping search" error. This occurs when
177     /// the caller requests an overlapping search while using an Aho-Corasick
178     /// automaton with a match kind other than [`MatchKind::Standard`].
179     ///
180     /// The match kind given should be the match kind of the automaton. It
181     /// should never be `MatchKind::Standard`.
unsupported_overlapping(got: MatchKind) -> MatchError182     pub fn unsupported_overlapping(got: MatchKind) -> MatchError {
183         MatchError::new(MatchErrorKind::UnsupportedOverlapping { got })
184     }
185 
186     /// Create a new "unsupported empty pattern" error. This occurs when the
187     /// caller requests a search for which matching an automaton that contains
188     /// an empty pattern string is not supported.
unsupported_empty() -> MatchError189     pub fn unsupported_empty() -> MatchError {
190         MatchError::new(MatchErrorKind::UnsupportedEmpty)
191     }
192 }
193 
194 /// The underlying kind of a [`MatchError`].
195 ///
196 /// This is a **non-exhaustive** enum. That means new variants may be added in
197 /// a semver-compatible release.
198 #[non_exhaustive]
199 #[derive(Clone, Debug, Eq, PartialEq)]
200 pub enum MatchErrorKind {
201     /// An error indicating that an anchored search was requested, but from a
202     /// searcher that was built without anchored support.
203     InvalidInputAnchored,
204     /// An error indicating that an unanchored search was requested, but from a
205     /// searcher that was built without unanchored support.
206     InvalidInputUnanchored,
207     /// An error indicating that a stream search was attempted on an
208     /// Aho-Corasick automaton with an unsupported `MatchKind`.
209     UnsupportedStream {
210         /// The match semantics for the automaton that was used.
211         got: MatchKind,
212     },
213     /// An error indicating that an overlapping search was attempted on an
214     /// Aho-Corasick automaton with an unsupported `MatchKind`.
215     UnsupportedOverlapping {
216         /// The match semantics for the automaton that was used.
217         got: MatchKind,
218     },
219     /// An error indicating that the operation requested doesn't support
220     /// automatons that contain an empty pattern string.
221     UnsupportedEmpty,
222 }
223 
224 #[cfg(feature = "std")]
225 impl std::error::Error for MatchError {}
226 
227 impl core::fmt::Display for MatchError {
fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result228     fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
229         match *self.kind() {
230             MatchErrorKind::InvalidInputAnchored => {
231                 write!(f, "anchored searches are not supported or enabled")
232             }
233             MatchErrorKind::InvalidInputUnanchored => {
234                 write!(f, "unanchored searches are not supported or enabled")
235             }
236             MatchErrorKind::UnsupportedStream { got } => {
237                 write!(
238                     f,
239                     "match kind {:?} does not support stream searching",
240                     got,
241                 )
242             }
243             MatchErrorKind::UnsupportedOverlapping { got } => {
244                 write!(
245                     f,
246                     "match kind {:?} does not support overlapping searches",
247                     got,
248                 )
249             }
250             MatchErrorKind::UnsupportedEmpty => {
251                 write!(
252                     f,
253                     "matching with an empty pattern string is not \
254                      supported for this operation",
255                 )
256             }
257         }
258     }
259 }
260