assemblyscript.go

Documentation: github.com/tetratelabs/wazero/imports/assemblyscript/example

     1  package main
     2  
     3  import (
     4  	"context"
     5  	_ "embed"
     6  	"fmt"
     7  	"log"
     8  	"os"
     9  	"strconv"
    10  
    11  	"github.com/tetratelabs/wazero"
    12  	"github.com/tetratelabs/wazero/imports/assemblyscript"
    13  )
    14  
    15  // asWasm compiled using `npm install && npm run build`
    16  //
    17  //go:embed testdata/index.wasm
    18  var asWasm []byte
    19  
    20  // main shows how to interact with a WebAssembly function that was compiled
    21  // from AssemblyScript
    22  //
    23  // See README.md for a full description.
    24  func main() {
    25  	// Choose the context to use for function calls.
    26  	ctx := context.Background()
    27  
    28  	// Create a new WebAssembly Runtime.
    29  	r := wazero.NewRuntime(ctx)
    30  	defer r.Close(ctx) // This closes everything this Runtime created.
    31  
    32  	// Instantiate a module implementing functions used by AssemblyScript.
    33  	// Thrown errors will be logged to os.Stderr
    34  	_, err := assemblyscript.Instantiate(ctx, r)
    35  	if err != nil {
    36  		log.Panicln(err)
    37  	}
    38  
    39  	// Instantiate a WebAssembly module that imports the "abort" and "trace"
    40  	// functions defined by assemblyscript.Instantiate and exports functions
    41  	// we'll use in this example.
    42  	mod, err := r.InstantiateWithConfig(ctx, asWasm,
    43  		// Override the default module config that discards stdout and stderr.
    44  		wazero.NewModuleConfig().WithStdout(os.Stdout).WithStderr(os.Stderr))
    45  	if err != nil {
    46  		log.Panicln(err)
    47  	}
    48  
    49  	// Get references to WebAssembly functions we'll use in this example.
    50  	helloWorld := mod.ExportedFunction("hello_world")
    51  	goodbyeWorld := mod.ExportedFunction("goodbye_world")
    52  
    53  	// Let's use the argument to this main function in Wasm.
    54  	numStr := os.Args[1]
    55  	num, err := strconv.Atoi(numStr)
    56  	if err != nil {
    57  		log.Panicln(err)
    58  	}
    59  
    60  	// Call hello_world, which returns the input value incremented by 3.
    61  	// While this calls trace(), our configuration didn't enable it.
    62  	results, err := helloWorld.Call(ctx, uint64(num))
    63  	if err != nil {
    64  		log.Panicln(err)
    65  	}
    66  	fmt.Printf("hello_world returned: %v", results[0])
    67  
    68  	// Call goodbye_world, which aborts with an error.
    69  	// assemblyscript.Instantiate was configured above to abort to stderr.
    70  	if _, err = goodbyeWorld.Call(ctx); err == nil {
    71  		log.Panicln("goodbye_world did not fail")
    72  	}
    73  }
    74
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