snarkvm_synthesizer_program/view/
mod.rs

1// Copyright (c) 2019-2026 Provable Inc.
2// This file is part of the snarkVM library.
3
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at:
7
8// http://www.apache.org/licenses/LICENSE-2.0
9
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16use crate::Command;
17
18mod input;
19pub use input::*;
20
21mod output;
22pub use output::*;
23
24mod bytes;
25mod parse;
26
27use console::{
28    network::{error, prelude::*},
29    program::{FinalizeType, Identifier, Register},
30};
31
32use indexmap::IndexSet;
33use std::collections::HashMap;
34
35/// A view function: a top-level, externally-callable, read-only block that returns typed values.
36///
37/// Views share the finalize command set (so they can `get`, `get.or_use`, `contains` against
38/// mappings), but cannot mutate state, schedule futures, or call other functions.
39#[derive(Clone, PartialEq, Eq)]
40pub struct ViewCore<N: Network> {
41    /// The name of the view function.
42    name: Identifier<N>,
43    /// The input statements, added in order of the input registers.
44    inputs: IndexSet<Input<N>>,
45    /// The commands, in order of execution.
46    commands: Vec<Command<N>>,
47    /// The output statements, in order of the desired output.
48    outputs: IndexSet<Output<N>>,
49    /// A mapping from `Position`s to their index in `commands`.
50    positions: HashMap<Identifier<N>, usize>,
51}
52
53impl<N: Network> ViewCore<N> {
54    /// Initializes a new view function with the given name.
55    pub fn new(name: Identifier<N>) -> Self {
56        Self {
57            name,
58            inputs: IndexSet::new(),
59            commands: Vec::new(),
60            outputs: IndexSet::new(),
61            positions: HashMap::new(),
62        }
63    }
64
65    /// Returns the name of the view function.
66    pub const fn name(&self) -> &Identifier<N> {
67        &self.name
68    }
69
70    /// Returns the view inputs.
71    pub const fn inputs(&self) -> &IndexSet<Input<N>> {
72        &self.inputs
73    }
74
75    /// Returns the view input types.
76    pub fn input_types(&self) -> Vec<FinalizeType<N>> {
77        self.inputs.iter().map(|input| input.finalize_type()).cloned().collect()
78    }
79
80    /// Returns the view commands.
81    pub fn commands(&self) -> &[Command<N>] {
82        &self.commands
83    }
84
85    /// Returns the view outputs.
86    pub const fn outputs(&self) -> &IndexSet<Output<N>> {
87        &self.outputs
88    }
89
90    /// Returns the view output types.
91    pub fn output_types(&self) -> Vec<FinalizeType<N>> {
92        self.outputs.iter().map(|output| output.finalize_type()).cloned().collect()
93    }
94
95    /// Returns the mapping of `Position`s to their index in `commands`.
96    pub const fn positions(&self) -> &HashMap<Identifier<N>, usize> {
97        &self.positions
98    }
99
100    /// Returns `true` if the view contains an array type with a size that exceeds the given maximum.
101    /// Mirrors `Finalize::exceeds_max_array_size` and additionally walks `outputs`, since views
102    /// declare typed outputs.
103    pub fn exceeds_max_array_size(&self, max_array_size: u32) -> bool {
104        self.inputs.iter().any(|input| {
105            matches!(input.finalize_type(), FinalizeType::Plaintext(p) if p.exceeds_max_array_size(max_array_size))
106        }) || self.commands.iter().any(|command| command.exceeds_max_array_size(max_array_size))
107            || self.outputs.iter().any(|output| {
108                matches!(output.finalize_type(), FinalizeType::Plaintext(p) if p.exceeds_max_array_size(max_array_size))
109            })
110    }
111
112    /// Returns `true` if the view refers to an external struct in its inputs, body, or outputs.
113    pub fn contains_external_struct(&self) -> bool {
114        self.inputs
115            .iter()
116            .any(|input| matches!(input.finalize_type(), FinalizeType::Plaintext(p) if p.contains_external_struct()))
117            || self
118                .commands
119                .iter()
120                .any(|command| matches!(command, Command::Instruction(inst) if inst.contains_external_struct()))
121            || self.outputs.iter().any(
122                |output| matches!(output.finalize_type(), FinalizeType::Plaintext(p) if p.contains_external_struct()),
123            )
124    }
125
126    /// Returns `true` if the view contains a string type. Mirrors `Finalize::contains_string_type`
127    /// and additionally walks `outputs`.
128    pub fn contains_string_type(&self) -> bool {
129        self.inputs
130            .iter()
131            .any(|input| matches!(input.finalize_type(), FinalizeType::Plaintext(p) if p.contains_string_type()))
132            || self.commands.iter().any(|command| command.contains_string_type())
133            || self
134                .outputs
135                .iter()
136                .any(|output| matches!(output.finalize_type(), FinalizeType::Plaintext(p) if p.contains_string_type()))
137    }
138}
139
140impl<N: Network> ViewCore<N> {
141    /// Adds the input statement to the view.
142    #[inline]
143    fn add_input(&mut self, input: Input<N>) -> Result<()> {
144        // Ensure there are no commands or outputs in memory.
145        ensure!(self.commands.is_empty(), "Cannot add inputs after commands have been added");
146        ensure!(self.outputs.is_empty(), "Cannot add inputs after outputs have been added");
147
148        // Ensure the maximum number of inputs has not been exceeded.
149        ensure!(self.inputs.len() < N::MAX_INPUTS, "Cannot add more than {} inputs", N::MAX_INPUTS);
150        // Ensure the input statement was not previously added.
151        ensure!(!self.inputs.contains(&input), "Cannot add duplicate input statement");
152
153        // Views are externally-callable; futures and dynamic futures are not meaningful here.
154        ensure!(
155            matches!(input.finalize_type(), FinalizeType::Plaintext(..)),
156            "View inputs must be plaintext (futures are forbidden)"
157        );
158
159        // Ensure the input register is a locator.
160        ensure!(matches!(input.register(), Register::Locator(..)), "Input register must be a locator");
161
162        self.inputs.insert(input);
163        Ok(())
164    }
165
166    /// Adds the given command to the view.
167    #[inline]
168    pub fn add_command(&mut self, command: Command<N>) -> Result<()> {
169        // Ensure there are no outputs already.
170        ensure!(self.outputs.is_empty(), "Cannot add commands after outputs have been added");
171
172        // Ensure the maximum number of commands has not been exceeded.
173        ensure!(self.commands.len() < N::MAX_COMMANDS, "Cannot add more than {} commands", N::MAX_COMMANDS);
174
175        // Reject any state-mutating or non-deterministic command.
176        ensure!(!command.is_write(), "Forbidden operation: view functions cannot use 'set' or 'remove'");
177        ensure!(!command.is_async(), "Forbidden operation: view functions cannot invoke an 'async' instruction");
178        ensure!(!command.is_await(), "Forbidden operation: view functions cannot 'await' a future");
179        ensure!(!command.is_call(), "Forbidden operation: view functions cannot 'call' another function");
180        ensure!(!command.is_instruction_for_record(), "Forbidden operation: view functions cannot operate on records");
181        // `rand.chacha` is only meaningful with finalize global state.
182        ensure!(!command.is_rand_chacha(), "Forbidden operation: view functions cannot use 'rand.chacha'");
183
184        // Check the destination registers.
185        for register in command.destinations() {
186            ensure!(matches!(register, Register::Locator(..)), "Destination register must be a locator");
187        }
188
189        // Branch target validation.
190        if let Some(position) = command.branch_to() {
191            ensure!(!self.positions.contains_key(position), "Cannot branch to an earlier position '{position}'");
192        }
193
194        if let Some(position) = command.position() {
195            ensure!(!self.positions.contains_key(position), "Cannot redefine position '{position}'");
196            ensure!(self.positions.len() < N::MAX_POSITIONS, "Cannot add more than {} positions", N::MAX_POSITIONS);
197            self.positions.insert(*position, self.commands.len());
198        }
199
200        self.commands.push(command);
201        Ok(())
202    }
203
204    /// Adds the output statement to the view.
205    #[inline]
206    fn add_output(&mut self, output: Output<N>) -> Result<()> {
207        // Ensure the maximum number of outputs has not been exceeded.
208        ensure!(self.outputs.len() < N::MAX_OUTPUTS, "Cannot add more than {} outputs", N::MAX_OUTPUTS);
209
210        // Views return plaintext only.
211        ensure!(
212            matches!(output.finalize_type(), FinalizeType::Plaintext(..)),
213            "View outputs must be plaintext (futures are forbidden)"
214        );
215
216        self.outputs.insert(output);
217        Ok(())
218    }
219}
220
221impl<N: Network> TypeName for ViewCore<N> {
222    #[inline]
223    fn type_name() -> &'static str {
224        "view"
225    }
226}
227
228#[cfg(test)]
229mod tests {
230    use super::*;
231
232    type CurrentNetwork = console::network::MainnetV0;
233
234    #[test]
235    fn test_add_input() {
236        let name = Identifier::from_str("view_core_test").unwrap();
237        let mut view = ViewCore::<CurrentNetwork>::new(name);
238
239        let input = Input::<CurrentNetwork>::from_str("input r0 as field.public;").unwrap();
240        assert!(view.add_input(input.clone()).is_ok());
241        assert!(view.add_input(input).is_err());
242    }
243
244    #[test]
245    fn test_reject_set_command() {
246        let name = Identifier::from_str("view_core_test").unwrap();
247        let mut view = ViewCore::<CurrentNetwork>::new(name);
248
249        let cmd = Command::<CurrentNetwork>::from_str("set 1u64 into balances[0u64];").unwrap();
250        let err = view.add_command(cmd).unwrap_err();
251        assert!(err.to_string().contains("'set' or 'remove'"));
252    }
253
254    #[test]
255    fn test_reject_remove_command() {
256        let name = Identifier::from_str("view_core_test").unwrap();
257        let mut view = ViewCore::<CurrentNetwork>::new(name);
258
259        let cmd = Command::<CurrentNetwork>::from_str("remove balances[0u64];").unwrap();
260        let err = view.add_command(cmd).unwrap_err();
261        assert!(err.to_string().contains("'set' or 'remove'"));
262    }
263
264    #[test]
265    fn test_reject_rand_chacha() {
266        let name = Identifier::from_str("view_core_test").unwrap();
267        let mut view = ViewCore::<CurrentNetwork>::new(name);
268
269        let cmd = Command::<CurrentNetwork>::from_str("rand.chacha into r0 as u64;").unwrap();
270        let err = view.add_command(cmd).unwrap_err();
271        assert!(err.to_string().contains("rand.chacha"));
272    }
273
274    #[test]
275    fn test_reject_await_command() {
276        let name = Identifier::from_str("view_core_test").unwrap();
277        let mut view = ViewCore::<CurrentNetwork>::new(name);
278
279        let cmd = Command::<CurrentNetwork>::from_str("await r0;").unwrap();
280        let err = view.add_command(cmd).unwrap_err();
281        assert!(err.to_string().contains("'await'"));
282    }
283
284    #[test]
285    fn test_reject_call_instruction() {
286        let name = Identifier::from_str("view_core_test").unwrap();
287        let mut view = ViewCore::<CurrentNetwork>::new(name);
288
289        let cmd = Command::<CurrentNetwork>::from_str("call foo r0 into r1;").unwrap();
290        let err = view.add_command(cmd).unwrap_err();
291        assert!(err.to_string().contains("'call'"));
292    }
293
294    #[test]
295    fn test_reject_cast_to_record() {
296        let name = Identifier::from_str("view_core_test").unwrap();
297        let mut view = ViewCore::<CurrentNetwork>::new(name);
298
299        let cmd =
300            Command::<CurrentNetwork>::from_str("cast r0.owner r0.token_amount into r1 as token.record;").unwrap();
301        let err = view.add_command(cmd).unwrap_err();
302        assert!(err.to_string().contains("operate on records"));
303    }
304
305    #[test]
306    fn test_reject_cast_to_dynamic_record() {
307        let name = Identifier::from_str("view_core_test").unwrap();
308        let mut view = ViewCore::<CurrentNetwork>::new(name);
309
310        let cmd = Command::<CurrentNetwork>::from_str("cast r0 into r1 as dynamic.record;").unwrap();
311        let err = view.add_command(cmd).unwrap_err();
312        assert!(err.to_string().contains("operate on records"));
313    }
314
315    #[test]
316    fn test_reject_get_record_dynamic() {
317        let name = Identifier::from_str("view_core_test").unwrap();
318        let mut view = ViewCore::<CurrentNetwork>::new(name);
319
320        let cmd = Command::<CurrentNetwork>::from_str("get.record.dynamic r0.x into r1 as bool;").unwrap();
321        let err = view.add_command(cmd).unwrap_err();
322        assert!(err.to_string().contains("operate on records"));
323    }
324
325    #[test]
326    fn test_reject_async_instruction() {
327        let name = Identifier::from_str("view_core_test").unwrap();
328        let mut view = ViewCore::<CurrentNetwork>::new(name);
329
330        let cmd = Command::<CurrentNetwork>::from_str("async foo r0 r1 into r3;").unwrap();
331        let err = view.add_command(cmd).unwrap_err();
332        assert!(err.to_string().contains("'async'"));
333    }
334}
snarkvm_synthesizer_program/view/mod.rs

snarkvm_synthesizer_program/view/
mod.rs
