rsaeb 0.8.0

A no_std + alloc interpreter for A=B ordered rewrite programs.
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

use alloc::vec::Vec;

use crate::allocation::{
    AllocationContext, AllocationError, RequestedCapacity, try_push, try_reserve_total_exact,
};
use crate::bytes::{Payload, RuntimeByte, RuntimeStateByteCount};

use super::state::MatchedStateSpan;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum RewriteRequest<'rule> {
    Replace(RewriteOperands<'rule>),
    MoveStart(RewriteOperands<'rule>),
    MoveEnd(RewriteOperands<'rule>),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) struct RewriteOperands<'rule> {
    state_match: MatchedStateSpan,
    rhs: &'rule Payload,
}

impl<'rule> RewriteOperands<'rule> {
    const fn new(state_match: MatchedStateSpan, rhs: &'rule Payload) -> Self {
        Self { state_match, rhs }
    }

    pub(crate) const fn state_match(self) -> MatchedStateSpan {
        self.state_match
    }

    pub(crate) const fn rhs(self) -> &'rule Payload {
        self.rhs
    }
}

impl<'rule> RewriteRequest<'rule> {
    pub(crate) const fn replace(state_match: MatchedStateSpan, rhs: &'rule Payload) -> Self {
        Self::Replace(RewriteOperands::new(state_match, rhs))
    }

    pub(crate) const fn move_start(state_match: MatchedStateSpan, rhs: &'rule Payload) -> Self {
        Self::MoveStart(RewriteOperands::new(state_match, rhs))
    }

    pub(crate) const fn move_end(state_match: MatchedStateSpan, rhs: &'rule Payload) -> Self {
        Self::MoveEnd(RewriteOperands::new(state_match, rhs))
    }

    pub(crate) const fn state_match(self) -> MatchedStateSpan {
        self.operands().state_match()
    }

    pub(crate) const fn rhs(self) -> &'rule Payload {
        self.operands().rhs()
    }

    pub(crate) const fn operands(self) -> RewriteOperands<'rule> {
        match self {
            Self::Replace(operands) | Self::MoveStart(operands) | Self::MoveEnd(operands) => {
                operands
            }
        }
    }
}

#[derive(Debug, PartialEq, Eq)]
pub(crate) struct RewriteScratch {
    bytes: Vec<RuntimeByte>,
}

#[derive(Debug, PartialEq, Eq)]
pub(crate) struct PreparedRewrite {
    bytes: Vec<RuntimeByte>,
}

impl PreparedRewrite {
    pub(crate) fn into_runtime_bytes(self) -> Vec<RuntimeByte> {
        self.bytes
    }
}

impl RewriteScratch {
    pub(crate) fn new() -> Self {
        Self { bytes: Vec::new() }
    }

    pub(crate) fn take_prepared(&mut self) -> PreparedRewrite {
        PreparedRewrite {
            bytes: core::mem::take(&mut self.bytes),
        }
    }

    pub(crate) fn store_previous_state(&mut self, bytes: Vec<RuntimeByte>) {
        self.bytes = bytes;
    }

    /// Clears scratch storage and reserves the requested rewrite capacity.
    ///
    /// # Errors
    ///
    /// Returns `AllocationError` if the rewrite scratch buffer cannot reserve
    /// the requested capacity.
    pub(crate) fn clear_and_reserve(
        &mut self,
        capacity: RuntimeStateByteCount,
    ) -> Result<(), AllocationError> {
        self.bytes.clear();
        try_reserve_total_exact(
            &mut self.bytes,
            RequestedCapacity::new(capacity.get()),
            AllocationContext::RuntimeRewriteState,
        )
    }

    /// Appends existing runtime bytes into scratch storage.
    ///
    /// # Errors
    ///
    /// Returns `AllocationError` if the rewrite scratch buffer cannot grow.
    pub(crate) fn push_existing(
        &mut self,
        source: impl IntoIterator<Item = RuntimeByte>,
    ) -> Result<(), AllocationError> {
        for byte in source {
            try_push(
                &mut self.bytes,
                byte,
                AllocationContext::RuntimeRewriteState,
            )?;
        }

        Ok(())
    }

    /// Appends program payload bytes into scratch storage.
    ///
    /// # Errors
    ///
    /// Returns `AllocationError` if the rewrite scratch buffer cannot grow.
    pub(crate) fn push_payload(&mut self, payload: &Payload) -> Result<(), AllocationError> {
        self.push_existing(payload.runtime_bytes())
    }
}