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expose parser.rs via a hack

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This commit is contained in:
Intege-rs
2025-11-28 02:12:33 -05:00
parent 9d0e3cbc3a
commit 8b8b506319
6 changed files with 503 additions and 479 deletions
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3
sub/_macros/src/lib.rs
View File

@@ -1,5 +1,8 @@
#![allow(unused)] #![allow(unused)]
// xpat's parser requires this
extern crate alloc;
mod from_repr; mod from_repr;
mod patterns; mod patterns;

487
sub/_macros/src/patterns.rs
View File

@@ -1,6 +1,15 @@
use core::{cmp, fmt, mem, str}; use core::{cmp, fmt, mem, str};
use proc_macro::{Literal, TokenStream, TokenTree}; use proc_macro::{Literal, TokenStream, TokenTree};
mod atoms {
include!("../../xpat/src/atoms.rs");
}
mod parser {
include!("../../xpat/src/parser.rs");
}
/// Compile time pattern parser. /// Compile time pattern parser.
/// ///
/// ```ignore /// ```ignore
@@ -14,7 +23,7 @@ pub fn proc_pattern(input: TokenStream) -> TokenStream {
_e => panic!("expected a single string literal to parse, got: {_e:?}"), _e => panic!("expected a single string literal to parse, got: {_e:?}"),
}; };
let pattern = match parse(&string) { let pattern = match parser::parse(&string) {
Ok(pattern) => pattern, Ok(pattern) => pattern,
Err(err) => panic!("invalid pattern syntax: {}", err), Err(err) => panic!("invalid pattern syntax: {}", err),
}; };
@@ -52,479 +61,3 @@ fn parse_str_literal(input: &Literal) -> String {
} }
string string
} }
/// Special skip value to indicate to use platform pointer size instead.
pub(crate) const PTR_SKIP: u8 = 0;
/// Pattern parsing error.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub struct ParsePatError {
kind: PatError,
position: usize,
}
impl fmt::Display for ParsePatError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Syntax Error @{}: {}.", self.position, self.kind.to_str())
}
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum PatError {
UnpairedHexDigit,
UnknownChar,
ManyOverflow,
ManyRange,
ManyInvalid,
SaveOverflow,
StackError,
StackInvalid,
UnclosedQuote,
AlignedOperand,
CheckOperand,
ReadOperand,
SubPattern,
SubOverflow,
DoubleNibble
}
impl PatError {
fn to_str(self) -> &'static str {
match self {
PatError::UnpairedHexDigit => "unpaired hex digit",
PatError::UnknownChar => "unknown character",
PatError::ManyOverflow => "many range exceeded",
PatError::ManyRange => "many bounds nonsensical",
PatError::ManyInvalid => "many invalid syntax",
PatError::SaveOverflow => "save store overflow",
PatError::StackError => "stack unbalanced",
PatError::StackInvalid => "stack must follow jump",
PatError::UnclosedQuote => "string missing end quote",
PatError::AlignedOperand => "aligned operand error",
PatError::CheckOperand => "aligned operand error",
PatError::ReadOperand => "read operand error",
PatError::SubPattern => "sub pattern error",
PatError::SubOverflow => "sub pattern too large",
PatError::DoubleNibble => "unpaired nibble wildcard",
}
}
}
//----------------------------------------------------------------
include!("../../xpat/src/atoms.rs");
/// Pattern parser.
///
/// # Remarks
///
/// Following are examples of the pattern syntax.
/// The syntax takes inspiration from [YARA hexadecimal strings](https://yara.readthedocs.io/en/v3.7.0/writingrules.html#hexadecimal-strings).
///
/// ```text
/// 55 89 e5 83 ? ec
/// ```
///
/// Case insensitive hexadecimal characters match the exact byte pattern and question marks serve as placeholders for unknown bytes.
///
/// Note that a single question mark matches a whole byte. The syntax to mask part of a byte is not yet available.
///
/// Spaces (code point 32) are completely optional and carry no semantic meaning, their purpose is to visually group things together.
///
/// ```text
/// b9 ' 37 13 00 00
/// ```
///
/// Single quotes are used as a bookmarks, to save the current cursor rva in the save array passed to the scanner.
///
/// It is no longer necessary to do tedious address calculations to read information out of the byte stream after a match was found.
/// This power really comes to life with the capability to follow relative and absolute references.
///
/// The first entry in the save array is reserved for the rva where the pattern was matched.
/// The rest of the save array is filled in order of appearance of the quotes. Here the rva of the quote can be found in `save[1]`.
///
/// ```text
/// b8 [16] 50 [13-42] ff
/// ```
///
/// Pairs of decimal numbers separated by a hypen in square brackets indicate the lower and upper bound of number of bytes to skip.
/// The scanner is non greedy and considers the first match while skipping as little as possible.
///
/// A single decimal number in square brackets without hypens is a fixed size jump, equivalent to writing that number of consecutive question marks.
///
/// ```text
/// 31 c0 74 % ' c3
/// e8 $ ' 31 c0 c3
/// 68 * ' 31 c0 c3
/// ```
///
/// These symbols are used to follow; a signed 1 byte relative jump: `%`, a signed 4 byte relative jump: `$` and an absolute pointer: `*`.
///
/// They are designed to be able to have the scanner follow short jumps, calls and longer jumps, and absolute pointers.
///
/// Composes really well with bookmarks to find the addresses of referenced functions and other data without tedious address calculations.
///
/// ```text
/// b8 * "STRING" 00
/// ```
///
/// String literals appear in double quotes and will be matched as UTF-8.
///
/// Escape sequences are not supported, switch back to matching with hex digits as needed.
/// For UTF-16 support, you are welcome to send a PR.
///
/// ```text
/// e8 $ { ' } 83 f0 5c c3
/// ```
///
/// Curly braces must follow a jump symbol (see above).
///
/// The sub pattern enclosed within the curly braces is matched at the destination after following the jump.
/// After the pattern successfully matched, the cursor returns to before the jump was followed.
/// The bytes defining the jump are skipped and matching continues again from here.
///
/// ```text
/// e8 $ @4
/// ```
///
/// Checks that the cursor is aligned at this point in the scan.
/// The align value is `(1 << arg)`, in this example the cursor is checked to be aligned to 16.
///
/// ```text
/// e8 i1 a0 u4
/// ```
///
/// An `i` or `u` indicates memory read operations followed by the size of the operand to read.
///
/// The read values are stored in the save array alongside the bookmarked addresses (single quotes).
/// This means the values are sign- or zero- extended respectively before being stored.
/// Operand sizes are 1 (byte), 2 (word) or 4 (dword).
///
/// The cursor is advanced by the size of the operand.
///
/// ```text
/// 83 c0 2a ( 6a ? | 68 ? ? ? ? ) e8
/// ```
///
/// Parentheses indicate alternate subpatterns separated by a pipe character.
///
/// The scanner attempts to match the alternate subpatterns from left to right and fails if none of them match.
pub fn parse(pat: &str) -> Result<Vec<Atom>, ParsePatError> {
let mut result = Vec::with_capacity(pat.len() / 2);
let mut pat_end = pat;
match parse_helper(&mut pat_end, &mut result) {
Ok(()) => Ok(result),
Err(kind) => {
let position = pat_end.as_ptr() as usize - pat.as_ptr() as usize;
Err(ParsePatError { kind, position })
},
}
}
// This is preferable but currently limited by macro rules...
// pub use crate::pattern as parse;
fn parse_helper(pat: &mut &str, result: &mut Vec<Atom>) -> Result<(), PatError> {
result.push(Atom::Save(0));
let mut iter = pat.as_bytes().iter();
let mut save = 1;
let mut depth = 0;
#[derive(Default)]
struct SubPattern {
case: usize,
brks: Vec<usize>,
save: u8,
save_next: u8,
depth: u8,
}
let mut subs = Vec::<SubPattern>::new();
while let Some(mut chr) = iter.next().cloned() {
match chr {
// Follow signed 1 byte jump
b'%' => result.push(Atom::Jump1),
// Follow signed 4 byte jump
b'$' => result.push(Atom::Jump4),
// Follow pointer
b'*' => result.push(Atom::Ptr),
// Start recursive operator
b'{' => {
depth += 1;
// Must follow a jump operator and insert push before the jump
let atom = match result.last_mut() {
Some(atom @ Atom::Jump1) => mem::replace(atom, Atom::Push(1)),
Some(atom @ Atom::Jump4) => mem::replace(atom, Atom::Push(4)),
Some(atom @ Atom::Ptr) => mem::replace(atom, Atom::Push(PTR_SKIP)),
_ => return Err(PatError::StackInvalid),
};
result.push(atom);
},
// End recursive operator
b'}' => {
// Unbalanced recursion
if depth <= 0 {
return Err(PatError::StackError);
}
depth -= 1;
result.push(Atom::Pop);
},
// Start subpattern
b'(' => {
subs.push(SubPattern::default());
let sub = subs.last_mut().unwrap();
// Keep the save and depth state
sub.save = save;
sub.depth = depth;
// Add a new case, update the case offset later
sub.case = result.len();
result.push(Atom::Case(0));
},
// Case subpattern
b'|' => {
// Should already have started a subpattern
let sub = subs.last_mut().ok_or(PatError::SubPattern)?;
// Update the save state
sub.save_next = cmp::max(sub.save_next, save);
save = sub.save;
depth = sub.depth;
// Add a break of the previous subpattern
sub.brks.push(result.len());
result.push(Atom::Break(0));
// Add a new case of the next subpattern
let case_offset = result.len() - sub.case - 1;
if case_offset >= 256 {
return Err(PatError::SubOverflow);
}
result[sub.case] = Atom::Case(case_offset as u8);
sub.case = result.len();
result.push(Atom::Case(0));
},
// End subpattern
b')' => {
// Should already have started a subpattern
let sub = subs.pop().ok_or(PatError::SubPattern)?;
// Prepare for the next save
save = cmp::max(sub.save_next, save);
depth = sub.depth;
// Neutralize the last case, since there are no more
result[sub.case] = Atom::Nop;
// Fill in the breaks
for &brk in &sub.brks {
let brk_offset = result.len() - brk - 1;
if brk_offset >= 256 {
return Err(PatError::SubOverflow);
}
result[brk] = Atom::Break(brk_offset as u8);
}
},
// Skip many operator
b'[' => {
// Parse the lower bound
let mut lower_bound = 0u32;
let mut at_least_one_char = false;
loop {
chr = iter.next().cloned().ok_or(PatError::ManyInvalid)?;
match chr {
b'-' | b']' => break,
chr @ b'0'..=b'9' => {
at_least_one_char = true;
lower_bound = lower_bound * 10 + (chr - b'0') as u32;
if lower_bound >= 16384 {
return Err(PatError::ManyOverflow);
}
},
_ => return Err(PatError::ManyInvalid),
}
}
if !at_least_one_char {
return Err(PatError::ManyInvalid);
}
// Turn the lower bound into skip ops
if lower_bound > 0 {
if lower_bound >= 256 {
result.push(Atom::Rangext((lower_bound >> 8) as u8));
}
result.push(Atom::Skip((lower_bound & 0xff) as u8));
}
// Second many part is optional
if chr == b']' {
continue;
}
// Parse the upper bound
let mut upper_bound = 0u32;
loop {
chr = iter.next().cloned().ok_or(PatError::ManyInvalid)?;
match chr {
b']' => break,
chr @ b'0'..=b'9' => {
upper_bound = upper_bound * 10 + (chr - b'0') as u32;
if upper_bound >= 16384 {
return Err(PatError::ManyOverflow);
}
},
_ => return Err(PatError::ManyInvalid),
}
}
// Lower bound should be strictly less than the upper bound
if lower_bound < upper_bound {
let many_skip = upper_bound - lower_bound;
if many_skip >= 256 {
result.push(Atom::Rangext((many_skip >> 8) as u8));
}
result.push(Atom::Many((many_skip & 0xff) as u8));
}
else {
return Err(PatError::ManyRange);
}
},
// Match a byte
b'0'..=b'9' | b'A'..=b'F' | b'a'..=b'f' | b'.' => {
let mut mask = 0xFF;
// High nibble of the byte
let hi = if chr == b'.' { mask &= 0x0F;0 }
else if chr >= b'a' { chr - b'a' + 10 }
else if chr >= b'A' { chr - b'A' + 10 }
else { chr - b'0' };
chr = iter.next().cloned().ok_or(PatError::UnpairedHexDigit)?;
// Low nibble of the byte
let lo = if chr >= b'a' && chr <= b'f' { chr - b'a' + 10 }
else if chr >= b'A' && chr <= b'F' { chr - b'A' + 10 }
else if chr >= b'0' && chr <= b'9' { chr - b'0' }
else if chr == b'.' { mask &= 0xF0; 0 }
else { return Err(PatError::UnpairedHexDigit); };
if mask == 0 { return Err(PatError::DoubleNibble); };
// mask out nibble
if mask != 0xFF { result.push(Atom::Fuzzy(mask)) }
// Add byte to the pattern
result.push(Atom::Byte((hi << 4) + lo));
},
// Match raw bytes
b'"' => {
loop {
if let Some(chr) = iter.next().cloned() {
if chr != b'"' {
result.push(Atom::Byte(chr));
}
else {
break;
}
}
else {
return Err(PatError::UnclosedQuote);
}
}
},
// Save the cursor
b'\'' => {
// 'Limited' save space
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
result.push(Atom::Save(save));
save += 1;
},
// Skip bytes
b'?' => {
// match result.last_mut() {
// Some(Atom::Skip(skip)) if *skip != PTR_SKIP && *skip < 127i8 => *skip += 1,
// _ => result.push(Atom::Skip(1)),
// };
// Coalescence skips together
if let Some(Atom::Skip(skip)) = result.last_mut() {
if *skip != PTR_SKIP && *skip < 255u8 {
*skip += 1;
continue;
}
}
result.push(Atom::Skip(1));
},
b'=' => {
let op = iter.next().cloned().ok_or(PatError::CheckOperand)?;
result.push( match op {
b'0'..=b'9' => Atom::Check(op - b'0'),
b'A'..=b'Z' => Atom::Check(10 + (op - b'A')),
b'a'..=b'z' => Atom::Check(10 + (op - b'a')),
_ => return Err(PatError::CheckOperand)
});
},
b'@' => {
let op = iter.next().cloned().ok_or(PatError::AlignedOperand)?;
result.push( match op {
b'0'..=b'9' => Atom::Aligned(op - b'0'),
b'A'..=b'Z' => Atom::Aligned(10 + (op - b'A')),
b'a'..=b'z' => Atom::Aligned(10 + (op - b'a')),
_ => return Err(PatError::AlignedOperand)
});
},
b'i' => {
let atom = match iter.next().cloned() {
Some(b'1') => Atom::ReadI8(save),
Some(b'2') => Atom::ReadI16(save),
Some(b'4') => Atom::ReadI32(save),
_ => return Err(PatError::ReadOperand),
};
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
save += 1;
result.push(atom);
},
b'u' => {
let atom = match iter.next().cloned() {
Some(b'1') => Atom::ReadU8(save),
Some(b'2') => Atom::ReadU16(save),
Some(b'4') => Atom::ReadU32(save),
_ => return Err(PatError::ReadOperand),
};
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
save += 1;
result.push(atom);
},
b'z' => {
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
result.push(Atom::Zero(save));
save += 1;
},
// Allow spaces as padding
b' ' | b'\n' | b'\r' | b'\t' => {},
// Everything else is illegal
_ => {
return Err(PatError::UnknownChar);
},
}
// Converted from str originally, should be safe
*pat = unsafe { str::from_utf8_unchecked(iter.as_slice()) };
}
// Check balanced stack operators
if depth != 0 {
return Err(PatError::StackError);
}
// Check if sub patterns are balanced
if subs.len() != 0 {
return Err(PatError::SubPattern);
}
// Remove redundant atoms at the end
fn is_redundant(atom: &Atom) -> bool {
match atom {
| Atom::Skip(_)
| Atom::Rangext(_)
| Atom::Pop
| Atom::Many(_) => true,
_ => false,
}
}
while result.last().map(is_redundant).unwrap_or(false) {
result.pop();
}
Ok(())
}

3
sub/xpat/Cargo.toml
View File

@@ -3,6 +3,9 @@ name = "sub_xpat"
version = "0.1.0" version = "0.1.0"
edition = "2021" edition = "2021"
[features]
alloc = []
[dependencies] [dependencies]
sub_core.workspace = true sub_core.workspace = true
sub_macros.workspace = true sub_macros.workspace = true

6
sub/xpat/src/hexdump.rs
View File

@@ -6,13 +6,15 @@ const SEP: &str = " | ";
pub struct HexDump<'s, T: Scannable + ?Sized, R: RangeBounds<usize>>(pub &'s T, pub R); pub struct HexDump<'s, T: Scannable + ?Sized, R: RangeBounds<usize>>(pub &'s T, pub R);
#[allow(clippy::needless_lifetimes)]
pub fn hex< pub fn hex<
'a,
T: Scannable + ?Sized, T: Scannable + ?Sized,
R: RangeBounds<usize> R: RangeBounds<usize>
>( >(
data: &T, data: &'a T,
range:R range:R
) -> HexDump<T, R> { ) -> HexDump<'a, T, R> {
HexDump(data, range) HexDump(data, range)
} }

6
sub/xpat/src/lib.rs
View File

@@ -8,6 +8,12 @@ pub mod scannable;
pub mod scanner; pub mod scanner;
pub mod hexdump; pub mod hexdump;
#[cfg(feature = "alloc")]
extern crate alloc;
#[cfg(feature = "alloc")]
pub mod parser;
// //
// Export Preludes: // Export Preludes:
// //

477
sub/xpat/src/parser.rs Normal file
View File

@@ -0,0 +1,477 @@
use core::{cmp, fmt, mem, str};
use super::atoms::Atom;
use alloc::vec::Vec;
/// Special skip value to indicate to use platform pointer size instead.
pub(crate) const PTR_SKIP: u8 = 0;
/// Pattern parsing error.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub struct ParsePatError {
kind: PatError,
position: usize,
}
impl fmt::Display for ParsePatError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Syntax Error @{}: {}.", self.position, self.kind.to_str())
}
}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum PatError {
UnpairedHexDigit,
UnknownChar,
ManyOverflow,
ManyRange,
ManyInvalid,
SaveOverflow,
StackError,
StackInvalid,
UnclosedQuote,
AlignedOperand,
CheckOperand,
ReadOperand,
SubPattern,
SubOverflow,
DoubleNibble
}
impl PatError {
fn to_str(self) -> &'static str {
match self {
PatError::UnpairedHexDigit => "unpaired hex digit",
PatError::UnknownChar => "unknown character",
PatError::ManyOverflow => "many range exceeded",
PatError::ManyRange => "many bounds nonsensical",
PatError::ManyInvalid => "many invalid syntax",
PatError::SaveOverflow => "save store overflow",
PatError::StackError => "stack unbalanced",
PatError::StackInvalid => "stack must follow jump",
PatError::UnclosedQuote => "string missing end quote",
PatError::AlignedOperand => "aligned operand error",
PatError::CheckOperand => "aligned operand error",
PatError::ReadOperand => "read operand error",
PatError::SubPattern => "sub pattern error",
PatError::SubOverflow => "sub pattern too large",
PatError::DoubleNibble => "unpaired nibble wildcard",
}
}
}
//----------------------------------------------------------------
/// Pattern parser.
///
/// # Remarks
///
/// Following are examples of the pattern syntax.
/// The syntax takes inspiration from [YARA hexadecimal strings](https://yara.readthedocs.io/en/v3.7.0/writingrules.html#hexadecimal-strings).
///
/// ```text
/// 55 89 e5 83 ? ec
/// ```
///
/// Case insensitive hexadecimal characters match the exact byte pattern and question marks serve as placeholders for unknown bytes.
///
/// Note that a single question mark matches a whole byte. The syntax to mask part of a byte is not yet available.
///
/// Spaces (code point 32) are completely optional and carry no semantic meaning, their purpose is to visually group things together.
///
/// ```text
/// b9 ' 37 13 00 00
/// ```
///
/// Single quotes are used as a bookmarks, to save the current cursor rva in the save array passed to the scanner.
///
/// It is no longer necessary to do tedious address calculations to read information out of the byte stream after a match was found.
/// This power really comes to life with the capability to follow relative and absolute references.
///
/// The first entry in the save array is reserved for the rva where the pattern was matched.
/// The rest of the save array is filled in order of appearance of the quotes. Here the rva of the quote can be found in `save[1]`.
///
/// ```text
/// b8 [16] 50 [13-42] ff
/// ```
///
/// Pairs of decimal numbers separated by a hypen in square brackets indicate the lower and upper bound of number of bytes to skip.
/// The scanner is non greedy and considers the first match while skipping as little as possible.
///
/// A single decimal number in square brackets without hypens is a fixed size jump, equivalent to writing that number of consecutive question marks.
///
/// ```text
/// 31 c0 74 % ' c3
/// e8 $ ' 31 c0 c3
/// 68 * ' 31 c0 c3
/// ```
///
/// These symbols are used to follow; a signed 1 byte relative jump: `%`, a signed 4 byte relative jump: `$` and an absolute pointer: `*`.
///
/// They are designed to be able to have the scanner follow short jumps, calls and longer jumps, and absolute pointers.
///
/// Composes really well with bookmarks to find the addresses of referenced functions and other data without tedious address calculations.
///
/// ```text
/// b8 * "STRING" 00
/// ```
///
/// String literals appear in double quotes and will be matched as UTF-8.
///
/// Escape sequences are not supported, switch back to matching with hex digits as needed.
/// For UTF-16 support, you are welcome to send a PR.
///
/// ```text
/// e8 $ { ' } 83 f0 5c c3
/// ```
///
/// Curly braces must follow a jump symbol (see above).
///
/// The sub pattern enclosed within the curly braces is matched at the destination after following the jump.
/// After the pattern successfully matched, the cursor returns to before the jump was followed.
/// The bytes defining the jump are skipped and matching continues again from here.
///
/// ```text
/// e8 $ @4
/// ```
///
/// Checks that the cursor is aligned at this point in the scan.
/// The align value is `(1 << arg)`, in this example the cursor is checked to be aligned to 16.
///
/// ```text
/// e8 i1 a0 u4
/// ```
///
/// An `i` or `u` indicates memory read operations followed by the size of the operand to read.
///
/// The read values are stored in the save array alongside the bookmarked addresses (single quotes).
/// This means the values are sign- or zero- extended respectively before being stored.
/// Operand sizes are 1 (byte), 2 (word) or 4 (dword).
///
/// The cursor is advanced by the size of the operand.
///
/// ```text
/// 83 c0 2a ( 6a ? | 68 ? ? ? ? ) e8
/// ```
///
/// Parentheses indicate alternate subpatterns separated by a pipe character.
///
/// The scanner attempts to match the alternate subpatterns from left to right and fails if none of them match.
pub fn parse(pat: &str) -> Result<Vec<Atom>, ParsePatError> {
let mut result = Vec::with_capacity(pat.len() / 2);
let mut pat_end = pat;
match parse_helper(&mut pat_end, &mut result) {
Ok(()) => Ok(result),
Err(kind) => {
let position = pat_end.as_ptr() as usize - pat.as_ptr() as usize;
Err(ParsePatError { kind, position })
},
}
}
// This is preferable but currently limited by macro rules...
// pub use crate::pattern as parse;
fn parse_helper(pat: &mut &str, result: &mut Vec<Atom>) -> Result<(), PatError> {
result.push(Atom::Save(0));
let mut iter = pat.as_bytes().iter();
let mut save = 1;
let mut depth = 0;
#[derive(Default)]
struct SubPattern {
case: usize,
brks: Vec<usize>,
save: u8,
save_next: u8,
depth: u8,
}
let mut subs = Vec::<SubPattern>::new();
while let Some(mut chr) = iter.next().cloned() {
match chr {
// Follow signed 1 byte jump
b'%' => result.push(Atom::Jump1),
// Follow signed 4 byte jump
b'$' => result.push(Atom::Jump4),
// Follow pointer
b'*' => result.push(Atom::Ptr),
// Start recursive operator
b'{' => {
depth += 1;
// Must follow a jump operator and insert push before the jump
let atom = match result.last_mut() {
Some(atom @ Atom::Jump1) => mem::replace(atom, Atom::Push(1)),
Some(atom @ Atom::Jump4) => mem::replace(atom, Atom::Push(4)),
Some(atom @ Atom::Ptr) => mem::replace(atom, Atom::Push(PTR_SKIP)),
_ => return Err(PatError::StackInvalid),
};
result.push(atom);
},
// End recursive operator
b'}' => {
// Unbalanced recursion
if depth <= 0 {
return Err(PatError::StackError);
}
depth -= 1;
result.push(Atom::Pop);
},
// Start subpattern
b'(' => {
subs.push(SubPattern::default());
let sub = subs.last_mut().unwrap();
// Keep the save and depth state
sub.save = save;
sub.depth = depth;
// Add a new case, update the case offset later
sub.case = result.len();
result.push(Atom::Case(0));
},
// Case subpattern
b'|' => {
// Should already have started a subpattern
let sub = subs.last_mut().ok_or(PatError::SubPattern)?;
// Update the save state
sub.save_next = cmp::max(sub.save_next, save);
save = sub.save;
depth = sub.depth;
// Add a break of the previous subpattern
sub.brks.push(result.len());
result.push(Atom::Break(0));
// Add a new case of the next subpattern
let case_offset = result.len() - sub.case - 1;
if case_offset >= 256 {
return Err(PatError::SubOverflow);
}
result[sub.case] = Atom::Case(case_offset as u8);
sub.case = result.len();
result.push(Atom::Case(0));
},
// End subpattern
b')' => {
// Should already have started a subpattern
let sub = subs.pop().ok_or(PatError::SubPattern)?;
// Prepare for the next save
save = cmp::max(sub.save_next, save);
depth = sub.depth;
// Neutralize the last case, since there are no more
result[sub.case] = Atom::Nop;
// Fill in the breaks
for &brk in &sub.brks {
let brk_offset = result.len() - brk - 1;
if brk_offset >= 256 {
return Err(PatError::SubOverflow);
}
result[brk] = Atom::Break(brk_offset as u8);
}
},
// Skip many operator
b'[' => {
// Parse the lower bound
let mut lower_bound = 0u32;
let mut at_least_one_char = false;
loop {
chr = iter.next().cloned().ok_or(PatError::ManyInvalid)?;
match chr {
b'-' | b']' => break,
chr @ b'0'..=b'9' => {
at_least_one_char = true;
lower_bound = lower_bound * 10 + (chr - b'0') as u32;
if lower_bound >= 16384 {
return Err(PatError::ManyOverflow);
}
},
_ => return Err(PatError::ManyInvalid),
}
}
if !at_least_one_char {
return Err(PatError::ManyInvalid);
}
// Turn the lower bound into skip ops
if lower_bound > 0 {
if lower_bound >= 256 {
result.push(Atom::Rangext((lower_bound >> 8) as u8));
}
result.push(Atom::Skip((lower_bound & 0xff) as u8));
}
// Second many part is optional
if chr == b']' {
continue;
}
// Parse the upper bound
let mut upper_bound = 0u32;
loop {
chr = iter.next().cloned().ok_or(PatError::ManyInvalid)?;
match chr {
b']' => break,
chr @ b'0'..=b'9' => {
upper_bound = upper_bound * 10 + (chr - b'0') as u32;
if upper_bound >= 16384 {
return Err(PatError::ManyOverflow);
}
},
_ => return Err(PatError::ManyInvalid),
}
}
// Lower bound should be strictly less than the upper bound
if lower_bound < upper_bound {
let many_skip = upper_bound - lower_bound;
if many_skip >= 256 {
result.push(Atom::Rangext((many_skip >> 8) as u8));
}
result.push(Atom::Many((many_skip & 0xff) as u8));
}
else {
return Err(PatError::ManyRange);
}
},
// Match a byte
b'0'..=b'9' | b'A'..=b'F' | b'a'..=b'f' | b'.' => {
let mut mask = 0xFF;
// High nibble of the byte
let hi = if chr == b'.' { mask &= 0x0F;0 }
else if chr >= b'a' { chr - b'a' + 10 }
else if chr >= b'A' { chr - b'A' + 10 }
else { chr - b'0' };
chr = iter.next().cloned().ok_or(PatError::UnpairedHexDigit)?;
// Low nibble of the byte
let lo = if chr >= b'a' && chr <= b'f' { chr - b'a' + 10 }
else if chr >= b'A' && chr <= b'F' { chr - b'A' + 10 }
else if chr >= b'0' && chr <= b'9' { chr - b'0' }
else if chr == b'.' { mask &= 0xF0; 0 }
else { return Err(PatError::UnpairedHexDigit); };
if mask == 0 { return Err(PatError::DoubleNibble); };
// mask out nibble
if mask != 0xFF { result.push(Atom::Fuzzy(mask)) }
// Add byte to the pattern
result.push(Atom::Byte((hi << 4) + lo));
},
// Match raw bytes
b'"' => {
loop {
if let Some(chr) = iter.next().cloned() {
if chr != b'"' {
result.push(Atom::Byte(chr));
}
else {
break;
}
}
else {
return Err(PatError::UnclosedQuote);
}
}
},
// Save the cursor
b'\'' => {
// 'Limited' save space
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
result.push(Atom::Save(save));
save += 1;
},
// Skip bytes
b'?' => {
// match result.last_mut() {
// Some(Atom::Skip(skip)) if *skip != PTR_SKIP && *skip < 127i8 => *skip += 1,
// _ => result.push(Atom::Skip(1)),
// };
// Coalescence skips together
if let Some(Atom::Skip(skip)) = result.last_mut() {
if *skip != PTR_SKIP && *skip < 255u8 {
*skip += 1;
continue;
}
}
result.push(Atom::Skip(1));
},
b'=' => {
let op = iter.next().cloned().ok_or(PatError::CheckOperand)?;
result.push( match op {
b'0'..=b'9' => Atom::Check(op - b'0'),
b'A'..=b'Z' => Atom::Check(10 + (op - b'A')),
b'a'..=b'z' => Atom::Check(10 + (op - b'a')),
_ => return Err(PatError::CheckOperand)
});
},
b'@' => {
let op = iter.next().cloned().ok_or(PatError::AlignedOperand)?;
result.push( match op {
b'0'..=b'9' => Atom::Aligned(op - b'0'),
b'A'..=b'Z' => Atom::Aligned(10 + (op - b'A')),
b'a'..=b'z' => Atom::Aligned(10 + (op - b'a')),
_ => return Err(PatError::AlignedOperand)
});
},
b'i' => {
let atom = match iter.next().cloned() {
Some(b'1') => Atom::ReadI8(save),
Some(b'2') => Atom::ReadI16(save),
Some(b'4') => Atom::ReadI32(save),
_ => return Err(PatError::ReadOperand),
};
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
save += 1;
result.push(atom);
},
b'u' => {
let atom = match iter.next().cloned() {
Some(b'1') => Atom::ReadU8(save),
Some(b'2') => Atom::ReadU16(save),
Some(b'4') => Atom::ReadU32(save),
_ => return Err(PatError::ReadOperand),
};
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
save += 1;
result.push(atom);
},
b'z' => {
if save >= u8::MAX {
return Err(PatError::SaveOverflow);
}
result.push(Atom::Zero(save));
save += 1;
},
// Allow spaces as padding
b' ' | b'\n' | b'\r' | b'\t' => {},
// Everything else is illegal
_ => {
return Err(PatError::UnknownChar);
},
}
// Converted from str originally, should be safe
*pat = unsafe { str::from_utf8_unchecked(iter.as_slice()) };
}
// Check balanced stack operators
if depth != 0 {
return Err(PatError::StackError);
}
// Check if sub patterns are balanced
if subs.len() != 0 {
return Err(PatError::SubPattern);
}
// Remove redundant atoms at the end
fn is_redundant(atom: &Atom) -> bool {
match atom {
| Atom::Skip(_)
| Atom::Rangext(_)
| Atom::Pop
| Atom::Many(_) => true,
_ => false,
}
}
while result.last().map(is_redundant).unwrap_or(false) {
result.pop();
}
Ok(())
}