solang 0.3.4

Solang Solidity Compiler
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
172
173
174
175
176

// SPDX-License-Identifier: Apache-2.0

use crate::sema::ast::{Expression, Mapping, Namespace, RetrieveType, Type};
use crate::sema::diagnostics::Diagnostics;
use crate::sema::expression::resolve_expression::expression;
use crate::sema::expression::{ExprContext, ResolveTo};
use crate::sema::symtable::Symtable;
use solang_parser::diagnostics::Diagnostic;
use solang_parser::pt;
use solang_parser::pt::CodeLocation;

/// Resolve an array subscript expression
pub(super) fn array_subscript(
    loc: &pt::Loc,
    array: &pt::Expression,
    index: &pt::Expression,
    context: &mut ExprContext,
    ns: &mut Namespace,
    symtable: &mut Symtable,
    diagnostics: &mut Diagnostics,
) -> Result<Expression, ()> {
    let mut array = expression(
        array,
        context,
        ns,
        symtable,
        diagnostics,
        ResolveTo::Unknown,
    )?;
    let array_ty = array.ty();

    if array.ty().is_mapping() {
        return mapping_subscript(loc, array, index, context, ns, symtable, diagnostics);
    }

    let index_width_ty = if array_ty.is_contract_storage() && !array_ty.is_storage_bytes() {
        Type::Uint(256)
    } else {
        Type::Uint(32)
    };

    let mut index = expression(
        index,
        context,
        ns,
        symtable,
        diagnostics,
        ResolveTo::Type(&index_width_ty),
    )?;

    let index_ty = index.ty();

    index.check_constant_overflow(diagnostics);

    match index_ty.deref_any() {
        Type::Uint(_) => (),
        _ => {
            diagnostics.push(Diagnostic::error(
                *loc,
                format!(
                    "array subscript must be an unsigned integer, not '{}'",
                    index.ty().to_string(ns)
                ),
            ));
            return Err(());
        }
    };

    if array_ty.is_storage_bytes() {
        return Ok(Expression::Subscript {
            loc: *loc,
            ty: Type::StorageRef(false, Box::new(Type::Bytes(1))),
            array_ty,
            array: Box::new(array),
            index: Box::new(index.cast(&index.loc(), &Type::Uint(32), false, ns, diagnostics)?),
        });
    }

    // make sure we load the index value if needed
    index = index.cast(&index.loc(), index_ty.deref_any(), true, ns, diagnostics)?;

    let deref_ty = array_ty.deref_any();
    match deref_ty {
        Type::Bytes(_) | Type::Array(..) | Type::DynamicBytes | Type::Slice(_) => {
            if array_ty.is_contract_storage() {
                let elem_ty = array_ty.storage_array_elem();

                // When subscripting a bytes32 type array, we need to load it. It is not
                // assignable and the value is calculated by shifting in codegen
                if let Type::Bytes(_) = deref_ty {
                    array = array.cast(&array.loc(), deref_ty, true, ns, diagnostics)?;
                }

                Ok(Expression::Subscript {
                    loc: *loc,
                    ty: elem_ty,
                    array_ty,
                    array: Box::new(array),
                    index: Box::new(index),
                })
            } else {
                let elem_ty = array_ty.array_deref();

                array = array.cast(
                    &array.loc(),
                    if array_ty.deref_memory().is_fixed_reference_type(ns) {
                        &array_ty
                    } else {
                        array_ty.deref_any()
                    },
                    true,
                    ns,
                    diagnostics,
                )?;

                Ok(Expression::Subscript {
                    loc: *loc,
                    ty: elem_ty,
                    array_ty,
                    array: Box::new(array),
                    index: Box::new(index),
                })
            }
        }
        Type::String => {
            diagnostics.push(Diagnostic::error(
                array.loc(),
                "array subscript is not permitted on string".to_string(),
            ));
            Err(())
        }
        _ => {
            diagnostics.push(Diagnostic::error(
                array.loc(),
                "expression is not an array".to_string(),
            ));
            Err(())
        }
    }
}

/// Calculate storage subscript
fn mapping_subscript(
    loc: &pt::Loc,
    mapping: Expression,
    index: &pt::Expression,
    context: &mut ExprContext,
    ns: &mut Namespace,
    symtable: &mut Symtable,
    diagnostics: &mut Diagnostics,
) -> Result<Expression, ()> {
    let ty = mapping.ty();
    let elem_ty = ty.storage_array_elem();

    if let Type::Mapping(Mapping { key, .. }) = ty.deref_any() {
        let index_expr = expression(
            index,
            context,
            ns,
            symtable,
            diagnostics,
            ResolveTo::Type(key),
        )?
        .cast(&index.loc(), key, true, ns, diagnostics)?;

        Ok(Expression::Subscript {
            loc: *loc,
            ty: elem_ty,
            array_ty: ty,
            array: Box::new(mapping),
            index: Box::new(index_expr),
        })
    } else {
        unreachable!()
    }
}