clash-brush-parser 0.5.3

POSIX/bash shell tokenizer and parsers (used by brush-shell)
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171

//! Parser for shell arithmetic expressions.

use crate::ast;
use crate::error;

/// Parses a shell arithmetic expression.
///
/// # Arguments
///
/// * `input` - The arithmetic expression to parse, in string form.
pub fn parse(input: &str) -> Result<ast::ArithmeticExpr, error::WordParseError> {
    cacheable_parse(input.to_owned())
}

#[cached::proc_macro::cached(size = 64, result = true)]
fn cacheable_parse(input: String) -> Result<ast::ArithmeticExpr, error::WordParseError> {
    tracing::debug!(target: "arithmetic", "parsing arithmetic expression: '{input}'");
    arithmetic::full_expression(input.as_str())
        .map_err(|e| error::WordParseError::ArithmeticExpression(e.into()))
}

peg::parser! {
    grammar arithmetic() for str {
        pub(crate) rule full_expression() -> ast::ArithmeticExpr =
            ![_] { ast::ArithmeticExpr::Literal(0) } /
            _ e:expression() _ { e }

        pub(crate) rule expression() -> ast::ArithmeticExpr = precedence!{
            x:(@) _ "," _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Comma, Box::new(x), Box::new(y)) }
            --
            x:lvalue() _ "*=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::Multiply, x, Box::new(y)) }
            x:lvalue() _ "/=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::Divide, x, Box::new(y)) }
            x:lvalue() _ "%=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::Modulo, x, Box::new(y)) }
            x:lvalue() _ "+=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::Add, x, Box::new(y)) }
            x:lvalue() _ "-=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::Subtract, x, Box::new(y)) }
            x:lvalue() _ "<<=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::ShiftLeft, x, Box::new(y)) }
            x:lvalue() _ ">>=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::ShiftRight, x, Box::new(y)) }
            x:lvalue() _ "&=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::BitwiseAnd, x, Box::new(y)) }
            x:lvalue() _ "|=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::BitwiseOr, x, Box::new(y)) }
            x:lvalue() _ "^=" _ y:(@) { ast::ArithmeticExpr::BinaryAssignment(ast::BinaryOperator::BitwiseXor, x, Box::new(y)) }
            x:lvalue() _ "=" _ y:(@) { ast::ArithmeticExpr::Assignment(x, Box::new(y)) }
            --
            x:@ _ "?" _ y:expression() _ ":" _ z:(@) { ast::ArithmeticExpr::Conditional(Box::new(x), Box::new(y), Box::new(z)) }
            --
            x:(@) _ "||" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::LogicalOr, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "&&" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::LogicalAnd, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "|" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::BitwiseOr, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "^" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::BitwiseXor, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "&" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::BitwiseAnd, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "==" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Equals, Box::new(x), Box::new(y)) }
            x:(@) _ "!=" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::NotEquals, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "<" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::LessThan, Box::new(x), Box::new(y)) }
            x:(@) _ ">" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::GreaterThan, Box::new(x), Box::new(y)) }
            x:(@) _ "<=" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::LessThanOrEqualTo, Box::new(x), Box::new(y)) }
            x:(@) _ ">=" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::GreaterThanOrEqualTo, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "<<" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::ShiftLeft, Box::new(x), Box::new(y)) }
            x:(@) _ ">>" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::ShiftRight, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "+" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Add, Box::new(x), Box::new(y)) }
            x:(@) _ "-" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Subtract, Box::new(x), Box::new(y)) }
            --
            x:(@) _ "*" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Multiply, Box::new(x), Box::new(y)) }
            x:(@) _ "%" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Modulo, Box::new(x), Box::new(y)) }
            x:(@) _ "/" _ y:@ { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Divide, Box::new(x), Box::new(y)) }
            --
            x:@ _ "**" _ y:(@) { ast::ArithmeticExpr::BinaryOp(ast::BinaryOperator::Power, Box::new(x), Box::new(y)) }
            --
            "!" _ x:(@) { ast::ArithmeticExpr::UnaryOp(ast::UnaryOperator::LogicalNot, Box::new(x)) }
            "~" _ x:(@) { ast::ArithmeticExpr::UnaryOp(ast::UnaryOperator::BitwiseNot, Box::new(x)) }
            --
            // NOTE: We add negative lookahead to avoid ambiguity with the pre-increment/pre-decrement operators.
            "+" !['+'] _ x:(@) { ast::ArithmeticExpr::UnaryOp(ast::UnaryOperator::UnaryPlus, Box::new(x)) }
            "-" !['-'] _ x:(@) { ast::ArithmeticExpr::UnaryOp(ast::UnaryOperator::UnaryMinus, Box::new(x)) }
            --
            "++" _ x:lvalue() { ast::ArithmeticExpr::UnaryAssignment(ast::UnaryAssignmentOperator::PrefixIncrement, x) }
            "--" _ x:lvalue() { ast::ArithmeticExpr::UnaryAssignment(ast::UnaryAssignmentOperator::PrefixDecrement, x) }
            --
            x:lvalue() _ "++" { ast::ArithmeticExpr::UnaryAssignment(ast::UnaryAssignmentOperator::PostfixIncrement, x) }
            x:lvalue() _ "--" { ast::ArithmeticExpr::UnaryAssignment(ast::UnaryAssignmentOperator::PostfixDecrement, x) }
            --
            n:literal_number() { ast::ArithmeticExpr::Literal(n) }
            l:lvalue() { ast::ArithmeticExpr::Reference(l) }
            "(" _ expr:expression() _ ")" { expr }
        }

        rule lvalue() -> ast::ArithmeticTarget =
            name:variable_name() "[" index:expression() "]" {
                ast::ArithmeticTarget::ArrayElement(name.to_owned(), Box::new(index))
            } /
            name:variable_name() {
                ast::ArithmeticTarget::Variable(name.to_owned())
            }

        rule variable_name() -> &'input str =
            $(['a'..='z' | 'A'..='Z' | '_'](['a'..='z' | 'A'..='Z' | '_' | '0'..='9']*))

        rule _() -> () = quiet!{[' ' | '\t' | '\n' | '\r']*} {}

        rule literal_number() -> i64 =
            // Literal with explicit radix (format: <base>#<literal>)
            radix:decimal_literal() "#" s:$(['0'..='9' | 'a'..='z' | 'A'..='Z' | '@' | '_']+) {?
                parse_shell_literal_number(s, radix.cast_unsigned())
            } /
            // Hex literal
            "0" ['x' | 'X'] s:$(['0'..='9' | 'a'..='f' | 'A'..='F']*) {?
                i64::from_str_radix(s, 16).or(Err("i64"))
            } /
            // Octal literal
            s:$("0" ['0'..='8']*) {?
                i64::from_str_radix(s, 8).or(Err("i64"))
            } /
            // Decimal literal
            decimal_literal()

        rule decimal_literal() -> i64 =
            s:$(['1'..='9'] ['0'..='9']*) {?
                // Parse as u64 first, then cast to i64. This handles values like
                // 9223372036854775808 (i64::MAX + 1) which is needed for INT64_MIN
                // when preceded by unary minus: -(9223372036854775808) wraps to i64::MIN.
                s.parse::<u64>().map(|v| v.cast_signed()).or(Err("i64"))
            }
    }
}

fn parse_shell_literal_number(s: &str, radix: u64) -> Result<i64, &'static str> {
    if !(2..=64).contains(&radix) {
        return Err("invalid base");
    }

    // For bases <= 36: case-insensitive (a-z and A-Z both map to 10-35)
    // For bases > 36 (bash extension):
    //   0-9 = 0-9, a-z = 10-35, A-Z = 36-61, @ = 62, _ = 63
    let mut result: i64 = 0;

    for ch in s.chars() {
        let digit_val = if radix <= 36 {
            match ch {
                '0'..='9' => (ch as u64) - ('0' as u64),
                'a'..='z' => (ch as u64) - ('a' as u64) + 10,
                'A'..='Z' => (ch as u64) - ('A' as u64) + 10,
                _ => return Err("invalid digit"),
            }
        } else {
            match ch {
                '0'..='9' => (ch as u64) - ('0' as u64),
                'a'..='z' => (ch as u64) - ('a' as u64) + 10,
                'A'..='Z' => (ch as u64) - ('A' as u64) + 36,
                '@' => 62,
                '_' => 63,
                _ => return Err("invalid digit"),
            }
        };

        if digit_val >= radix {
            return Err("value too great for base");
        }

        result = result
            .wrapping_mul(radix.cast_signed())
            .wrapping_add(digit_val.cast_signed());
    }

    Ok(result)
}