lvm-class 0.4.1

JVM class file parser and writer for the Lagertha VM project
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

//! Type annotation types for class file attributes.
//!
//! https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.20

use super::annotation::ElementValuePair;
use crate::ClassFormatErr;
use lvm_common::utils::cursor::ByteCursor;

/// Target information for a type annotation, identifying where the type is used.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum TargetInfo {
    TypeParameter {
        type_parameter_index: u8,
    },
    Supertype {
        supertype_index: u16,
    },
    TypeParameterBound {
        type_parameter_index: u8,
        bound_index: u8,
    },
    Empty,
    MethodFormalParameter {
        formal_parameter_index: u8,
    },
    Throws {
        throws_type_index: u16,
    },
    LocalVar {
        localvar_table: Vec<LocalVarEntry>,
    },
    Catch {
        exception_table_index: u16,
    },
    Offset {
        offset: u16,
    },
    TypeArgument {
        offset: u16,
        type_argument_index: u8,
    },
}

/// An entry in the local variable table for type annotations.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct LocalVarEntry {
    pub start_pc: u16,
    pub length: u16,
    pub index: u16,
}

/// A path to a specific nested type within a compound type.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TypePath {
    pub path: Vec<TypePathEntry>,
}

/// A single step in a type path.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TypePathEntry {
    pub type_path_kind: u8,
    pub type_argument_index: u8,
}

/// A type annotation with its target and path information.
///
/// https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.20
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TypeAnnotation {
    pub target_info: TargetInfo,
    pub target_path: TypePath,
    pub type_index: u16,
    pub element_value_pairs: Vec<ElementValuePair>,
}

impl<'a> TypeAnnotation {
    pub(crate) fn read(cursor: &mut ByteCursor<'a>) -> Result<Self, ClassFormatErr> {
        let target_type = cursor.u8()?;

        let target_info = match target_type {
            0x00 => TargetInfo::TypeParameter {
                type_parameter_index: cursor.u8()?,
            },
            0x01 => TargetInfo::Supertype {
                supertype_index: cursor.u16()?,
            },
            0x10 => TargetInfo::TypeParameterBound {
                type_parameter_index: cursor.u8()?,
                bound_index: cursor.u8()?,
            },
            0x11 => TargetInfo::Empty,
            0x12 => TargetInfo::MethodFormalParameter {
                formal_parameter_index: cursor.u8()?,
            },
            0x13 => TargetInfo::Throws {
                throws_type_index: cursor.u16()?,
            },
            0x14 => {
                let table_length = cursor.u16()?;
                let mut localvar_table = Vec::with_capacity(table_length as usize);
                for _ in 0..table_length {
                    localvar_table.push(LocalVarEntry {
                        start_pc: cursor.u16()?,
                        length: cursor.u16()?,
                        index: cursor.u16()?,
                    });
                }
                TargetInfo::LocalVar { localvar_table }
            }
            0x15 => TargetInfo::Catch {
                exception_table_index: cursor.u16()?,
            },
            0x16 => TargetInfo::Offset {
                offset: cursor.u16()?,
            },
            0x17 => TargetInfo::TypeArgument {
                offset: cursor.u16()?,
                type_argument_index: cursor.u8()?,
            },
            _ => unimplemented!(),
        };

        // Read type_path
        let path_length = cursor.u8()?;
        let mut path = Vec::with_capacity(path_length as usize);
        for _ in 0..path_length {
            path.push(TypePathEntry {
                type_path_kind: cursor.u8()?,
                type_argument_index: cursor.u8()?,
            });
        }
        let target_path = TypePath { path };

        // Read annotation data
        let type_index = cursor.u16()?;
        let num_element_value_pairs = cursor.u16()?;
        let mut element_value_pairs = Vec::with_capacity(num_element_value_pairs as usize);
        for _ in 0..num_element_value_pairs {
            element_value_pairs.push(ElementValuePair::read(cursor)?);
        }

        Ok(Self {
            target_info,
            target_path,
            type_index,
            element_value_pairs,
        })
    }
}