Implement basic printing strategy

Author: dy

readme.md

@@ -92,7 +92,7 @@ const tree = [
 const str = print(tree, {
   indent: '  ',   // indentation characters
   newline: '\n',  // new line charactes
-  pad: 1,         // pad start of each line
+  pad: '',        // pad start of each line with a string
   comments: true  // keep comments
 })
 // (func (export "double")

src/print.js

@@ -0,0 +1,48 @@
+import parse from './parse.js';
+
+let indent = '', newline = '\n', pad = '', comments = false, _i = 0
+
+export default function print(tree, options = {}) {
+  if (typeof tree === 'string') tree = parse(tree);
+
+  ({ indent, newline, pad, comments } = options);
+  newline ||= ''
+  pad ||= ''
+  indent ||= ''
+
+  let out = typeof tree[0] === 'string' ? printNode(tree) : tree.map(node => printNode(node)).join(newline)
+
+  return out
+}
+
+const flats = ['param', 'local', 'global', 'result', 'export']
+
+function printNode(node, level = 0) {
+  if (!Array.isArray(node)) return node + ''
+
+  let content = node[0]
+
+  for (let i = 1; i < node.length; i++) {
+    // new node doesn't need space separator, eg. [x,[y]] -> `x(y)`
+    if (Array.isArray(node[i])) {
+      // inline nodes like (param x)(param y)
+      // (func (export "xxx")..., but not (func (export "a")(param "b")...
+      if (
+        flats.includes(node[i][0]) &&
+        (!Array.isArray(node[i - 1]) || node[i][0] === node[i - 1][0])
+      ) {
+        if (!Array.isArray(node[i - 1])) content += ` `
+      } else {
+        content += newline
+        if (node[i]) content += indent.repeat(level + 1)
+      }
+
+      content += printNode(node[i], level + 1)
+    }
+    else {
+      content += ` `
+      content += node[i]
+    }
+  }
+  return `(${content})`
+}

test/compile.js

@@ -1170,7 +1170,7 @@ t.skip('bench: brownian', async () => {
   console.timeEnd('wabt')
 })
 
-async function file(path) {
+export async function file(path) {
   let res = await fetch(path)
   let src = await res.text()
   return src
@@ -1183,17 +1183,6 @@ async function runExample(path) {
   // const mod = new WebAssembly.Module(buffer)
 }
 
-// stub fetch for local purpose
-const isNode = typeof global !== 'undefined' && globalThis === global
-if (isNode) {
-  let { readFileSync } = await import('fs')
-  globalThis.fetch = async path => {
-    path = `.${path}`
-    const data = readFileSync(path, 'utf8')
-    return { text() { return data } }
-  }
-}
-
 console.hex = (d) => console.log((Object(d).buffer instanceof ArrayBuffer ? new Uint8Array(d.buffer) :
   typeof d === 'string' ? (new TextEncoder('utf-8')).encode(d) :
     new Uint8ClampedArray(d)).reduce((p, c, i, a) => p + (i % 16 === 0 ? i.toString(16).padStart(6, 0) + '  ' : ' ') +
@@ -1215,7 +1204,7 @@ const hex = (str, ...fields) =>
   )
 
 // convert wast code to binary via Wabt
-function wat2wasm(code, config) {
+export function wat2wasm(code, config) {
   let metrics = config ? config.metrics : true
   const parsed = wabt.parseWat('inline', code, {})
   metrics && console.time('wabt build')

test/index.html

@@ -1,6 +1,6 @@
 <doctype html>
 
-<script type="importmap">
+  <script type="importmap">
 {
   "imports": {
     "tst": "../node_modules/tst/tst.js",
@@ -10,5 +10,6 @@
 }
 </script>
 
-<script src="./parse.js" type="module"></script>
-<script src="./compile.js" type="module"></script>
+  <script src="./parse.js" type="module"></script>
+  <script src="./compile.js" type="module"></script>
+  <script src="./print.js" type="module"></script>

test/index.js

@@ -1,2 +1,14 @@
 import './parse.js'
 import './compile.js'
+import './print.js'
+
+// stub fetch for local purpose
+const isNode = typeof global !== 'undefined' && globalThis === global
+if (isNode) {
+  let { readFileSync } = await import('fs')
+  globalThis.fetch = async path => {
+    path = `.${path}`
+    const data = readFileSync(path, 'utf8')
+    return { text() { return data } }
+  }
+}

test/print.js

@@ -0,0 +1,49 @@
+import t, { is, ok, same } from 'tst'
+import print from '../src/print.js'
+import { wat2wasm, file } from './compile.js'
+
+t.only('print: basics', () => {
+  const tree = [
+    'func', ['export', '"double"'], ['param', 'f64', 'f32'], ['param', '$x', 'i32'], ['result', 'f64'],
+    ['f64.mul', ['local.get', 0], ['f64.const', 2]]
+  ]
+
+  // minify
+  const min = print(tree, {
+    indent: false,
+    newline: false,
+    pad: false,
+    comments: false
+  })
+  wat2wasm(min)
+  is(min, `(func (export "double")(param f64 f32)(param $x i32)(result f64)(f64.mul(local.get 0)(f64.const 2)))`)
+
+  // pretty-print
+  const pretty = print(tree, {
+    indent: '  ',   // indentation characters
+    newline: '\n',  // new line charactes
+    pad: '',        // pad start of each line with a string
+    comments: true  // keep comments
+  })
+  wat2wasm(pretty)
+  is(pretty,
+    `(func (export "double")
+  (param f64 f32)(param $x i32)
+  (result f64)
+  (f64.mul
+    (local.get 0)
+    (f64.const 2)))`)
+
+  is(
+    print(`(import "Math" "random" (func $random (result f32)))`),
+    `(import \"Math\" \"random\"(func $random (result f32)))`
+  )
+})
+
+t.only('print: dino', async t => {
+  let src = await file('./example/dino.wat')
+  const dino = print(src)
+  console.log(dino)
+
+  wat2wasm(dino)
+})