45 lines
1.8 KiB
Rust
45 lines
1.8 KiB
Rust
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// In this example we execute a contract funciton exported as "_call"
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extern crate wasmi;
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use std::env::args;
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use std::fs::File;
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use wasmi::{ModuleInstance, NopExternals, RuntimeValue, ImportsBuilder, load_from_buffer, LoadedModule};
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fn load_from_file(filename: &str) -> LoadedModule {
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use std::io::prelude::*;
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let mut file = File::open(filename).unwrap();
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let mut buf = Vec::new();
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file.read_to_end(&mut buf).unwrap();
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load_from_buffer(buf).unwrap()
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}
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fn main() {
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let args: Vec<_> = args().collect();
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if args.len() != 3 {
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println!("Usage: {} <wasm file> <arg>", args[0]);
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println!(" wasm file should contain exported `_call` function with single I32 argument");
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return;
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}
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// Here we load module using dedicated for this purpose
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// `load_from_file` function (which works only with modules)
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let module = load_from_file(&args[1]);
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// Intialize deserialized module. It adds module into It expects 3 parameters:
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// - a name for the module
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// - a module declaration
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// - "main" module doesn't import native module(s) this is why we don't need to provide external native modules here
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// This test shows how to implement native module https://github.com/NikVolf/parity-wasm/blob/master/src/interpreter/tests/basics.rs#L197
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let main = ModuleInstance::new(&module, &ImportsBuilder::default())
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.expect("Failed to instantiate module")
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.run_start(&mut NopExternals)
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.expect("Failed to run start function in module");
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// The argument should be parsable as a valid integer
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let argument: i32 = args[2].parse().expect("Integer argument required");
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// "_call" export of function to be executed with an i32 argument and prints the result of execution
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println!("Result: {:?}", main.invoke_export("_call", &[RuntimeValue::I32(argument)], &mut NopExternals));
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}
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