1// (C) Copyright 2016 Jethro G. Beekman
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8//! A C expression parser and evaluator.
9//!
10//! This crate provides methods for parsing and evaluating simple C expressions. In general, the
11//! crate can handle most arithmetic expressions that would appear in macros or the definition of
12//! constants, as well as string and character constants.
13//!
14//! The main entry point for is [`token::parse`], which parses a byte string and returns its
15//! evaluated value.
16#![warn(rust_2018_idioms)]
17#![warn(missing_docs)]
18#![allow(deprecated)]
19
20pub mod nom {
21 //! nom's result types, re-exported.
22 pub use nom::{error::ErrorKind, error::Error, Err, IResult, Needed};
23}
24pub mod expr;
25pub mod literal;
26pub mod token;
27
28/// Parsing errors specific to C parsing
29#[derive(Debug)]
30pub enum ErrorKind {
31 /// Expected the specified token
32 ExactToken(token::Kind, &'static [u8]),
33 /// Expected one of the specified tokens
34 ExactTokens(token::Kind, &'static [&'static str]),
35 /// Expected a token of the specified kind
36 TypedToken(token::Kind),
37 /// An unknown identifier was encountered
38 UnknownIdentifier,
39 /// An invalid literal was encountered.
40 ///
41 /// When encountered, this generally means a bug exists in the data that
42 /// was passed in or the parsing logic.
43 InvalidLiteral,
44 /// A full parse was requested, but data was left over after parsing finished.
45 Partial,
46 /// An error occurred in an underlying nom parser.
47 Parser(nom::ErrorKind),
48}
49
50impl From<nom::ErrorKind> for ErrorKind {
51 fn from(k: nom::ErrorKind) -> Self {
52 ErrorKind::Parser(k)
53 }
54}
55
56impl From<u32> for ErrorKind {
57 fn from(_: u32) -> Self {
58 ErrorKind::InvalidLiteral
59 }
60}
61
62/// Parsing errors specific to C parsing.
63///
64/// This is a superset of `(I, nom::ErrorKind)` that includes the additional errors specified by
65/// [`ErrorKind`].
66#[derive(Debug)]
67pub struct Error<I> {
68 /// The remainder of the input stream at the time of the error.
69 pub input: I,
70 /// The error that occurred.
71 pub error: ErrorKind,
72}
73
74impl<I> From<(I, nom::ErrorKind)> for Error<I> {
75 fn from(e: (I, nom::ErrorKind)) -> Self {
76 Self::from((e.0, ErrorKind::from(e.1)))
77 }
78}
79
80impl<I> From<(I, ErrorKind)> for Error<I> {
81 fn from(e: (I, ErrorKind)) -> Self {
82 Self {
83 input: e.0,
84 error: e.1,
85 }
86 }
87}
88
89impl<I> From<::nom::error::Error<I>> for Error<I> {
90 fn from(e: ::nom::error::Error<I>) -> Self {
91 Self {
92 input: e.input,
93 error: e.code.into(),
94 }
95 }
96}
97
98impl<I> ::nom::error::ParseError<I> for Error<I> {
99 fn from_error_kind(input: I, kind: nom::ErrorKind) -> Self {
100 Self {
101 input,
102 error: kind.into(),
103 }
104 }
105
106 fn append(_: I, _: nom::ErrorKind, other: Self) -> Self {
107 other
108 }
109}
110
111// in lieu of https://github.com/Geal/nom/issues/1010
112trait ToCexprResult<I, O> {
113 fn to_cexpr_result(self) -> nom::IResult<I, O, Error<I>>;
114}
115impl<I, O, E> ToCexprResult<I, O> for nom::IResult<I, O, E>
116where
117 Error<I>: From<E>,
118{
119 fn to_cexpr_result(self) -> nom::IResult<I, O, Error<I>> {
120 match self {
121 Ok(v: (I, O)) => Ok(v),
122 Err(nom::Err::Incomplete(n: Needed)) => Err(nom::Err::Incomplete(n)),
123 Err(nom::Err::Error(e: E)) => Err(nom::Err::Error(e.into())),
124 Err(nom::Err::Failure(e: E)) => Err(nom::Err::Failure(e.into())),
125 }
126 }
127}
128
129/// If the input result indicates a succesful parse, but there is data left,
130/// return an `Error::Partial` instead.
131pub fn assert_full_parse<'i, I: 'i, O, E>(
132 result: nom::IResult<&'i [I], O, E>,
133) -> nom::IResult<&'i [I], O, Error<&'i [I]>>
134where
135 Error<&'i [I]>: From<E>,
136{
137 match result.to_cexpr_result() {
138 Ok((rem: &'i [I], output: O)) => {
139 if rem.is_empty() {
140 Ok((rem, output))
141 } else {
142 Err(nom::Err::Error((rem, ErrorKind::Partial).into()))
143 }
144 }
145 Err(nom::Err::Incomplete(n: Needed)) => Err(nom::Err::Incomplete(n)),
146 Err(nom::Err::Failure(e: Error<&'i [I]>)) => Err(nom::Err::Failure(e)),
147 Err(nom::Err::Error(e: Error<&'i [I]>)) => Err(nom::Err::Error(e)),
148 }
149}
150