toml: add Stringify feature (denoland/deno_std#319)

Original: https://github.com/denoland/deno_std/commit/1e589b95532fd3575b81df65a2a99f7004f8ea1b

4 files changed, 265 insertions, 4 deletions

diff --git a/strings/pad.ts b/strings/pad.ts
index 1c1868769..3c5084da2 100644
--- a/strings/pad.ts
+++ b/strings/pad.ts
@@ -3,9 +3,9 @@
 /** FillOption Object */
 export interface FillOption {
   /** Char to fill in */
-  char: string;
+  char?: string;
   /** Side to fill in */
-  side: "left" | "right";
+  side?: "left" | "right";
   /** If strict, output string can't be greater than strLen*/
   strict?: boolean;
   /** char/string used to specify the string has been truncated */
@@ -54,7 +54,7 @@ export function pad(
   let out = input;
   const outL = out.length;
   if (outL < strLen) {
-    if (opts.side === "left") {
+    if (!opts.side || opts.side === "left") {
       out = out.padStart(strLen, opts.char);
     } else {
       out = out.padEnd(strLen, opts.char);
diff --git a/toml/README.md b/toml/README.md
index b19974b2e..f4ae25857 100644
--- a/toml/README.md
+++ b/toml/README.md
@@ -91,6 +91,8 @@ will output:
 
 ## Usage
 
+### Parse
+
 ```ts
 import { parseFile, parse } from "./parser.ts";
 
@@ -99,3 +101,17 @@ const tomlObject = parseFile("file.toml");
 const tomlString = 'foo.bar = "Deno"';
 const tomlObject22 = parse(tomlString);
 ```
+
+### Stringify
+
+```ts
+import { stringify } from "./parser.ts";
+const obj = {
+  bin: [
+    { name: "deno", path: "cli/main.rs" },
+    { name: "deno_core", path: "src/foo.rs" }
+  ],
+  nib: [{ name: "node", path: "not_found" }]
+};
+const tomlString = stringify(obj);
+```
diff --git a/toml/parser.ts b/toml/parser.ts
index 09203775a..a7dd97750 100644
--- a/toml/parser.ts
+++ b/toml/parser.ts
@@ -1,6 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import { existsSync } from "../fs/exists.ts";
 import { deepAssign } from "../util/deep_assign.ts";
+import { pad } from "../strings/pad.ts";
 
 class KeyValuePair {
   key: string;
@@ -381,6 +382,156 @@ class Parser {
   }
 }
 
+class Dumper {
+  maxPad: number = 0;
+  srcObject: object;
+  output: string[] = [];
+  constructor(srcObjc: object) {
+    this.srcObject = srcObjc;
+  }
+  dump(): string[] {
+    this.output = this._parse(this.srcObject);
+    this.output = this._format();
+    return this.output;
+  }
+  _parse(obj: object, path: string = ""): string[] {
+    const out = [];
+    const props = Object.keys(obj);
+    const propObj = props.filter(
+      e =>
+        (obj[e] instanceof Array && !this._isSimplySerializable(obj[e][0])) ||
+        !this._isSimplySerializable(obj[e])
+    );
+    const propPrim = props.filter(
+      e =>
+        !(obj[e] instanceof Array && !this._isSimplySerializable(obj[e][0])) &&
+        this._isSimplySerializable(obj[e])
+    );
+    const k = propPrim.concat(propObj);
+    for (let i = 0; i < k.length; i++) {
+      const prop = k[i];
+      const value = obj[prop];
+      if (value instanceof Date) {
+        out.push(this._dateDeclaration(prop, value));
+      } else if (typeof value === "string" || value instanceof RegExp) {
+        out.push(this._strDeclaration(prop, value.toString()));
+      } else if (typeof value === "number") {
+        out.push(this._numberDeclaration(prop, value));
+      } else if (
+        value instanceof Array &&
+        this._isSimplySerializable(value[0])
+      ) {
+        // only if primitives types in the array
+        out.push(this._arrayDeclaration(prop, value));
+      } else if (
+        value instanceof Array &&
+        !this._isSimplySerializable(value[0])
+      ) {
+        // array of objects
+        for (let i = 0; i < value.length; i++) {
+          out.push("");
+          out.push(this._headerGroup(path + prop));
+          out.push(...this._parse(value[i], `${path}${prop}.`));
+        }
+      } else if (typeof value === "object") {
+        out.push("");
+        out.push(this._header(path + prop));
+        out.push(...this._parse(value, `${path}${prop}.`));
+      }
+    }
+    out.push("");
+    return out;
+  }
+  _isSimplySerializable(value: unknown): boolean {
+    return (
+      typeof value === "string" ||
+      typeof value === "number" ||
+      value instanceof RegExp ||
+      value instanceof Date ||
+      value instanceof Array
+    );
+  }
+  _header(title: string): string {
+    return `[${title}]`;
+  }
+  _headerGroup(title: string): string {
+    return `[[${title}]]`;
+  }
+  _declaration(title: string): string {
+    if (title.length > this.maxPad) {
+      this.maxPad = title.length;
+    }
+    return `${title} = `;
+  }
+  _arrayDeclaration(title: string, value: unknown[]): string {
+    return `${this._declaration(title)}${JSON.stringify(value)}`;
+  }
+  _strDeclaration(title: string, value: string): string {
+    return `${this._declaration(title)}"${value}"`;
+  }
+  _numberDeclaration(title: string, value: number): string {
+    switch (value) {
+      case Infinity:
+        return `${this._declaration(title)}inf`;
+      case -Infinity:
+        return `${this._declaration(title)}-inf`;
+      default:
+        return `${this._declaration(title)}${value}`;
+    }
+  }
+  _dateDeclaration(title: string, value: Date): string {
+    function dtPad(v: string, lPad: number = 2): string {
+      return pad(v, lPad, { char: "0" });
+    }
+    let m = dtPad((value.getUTCMonth() + 1).toString());
+    let d = dtPad(value.getUTCDate().toString());
+    const h = dtPad(value.getUTCHours().toString());
+    const min = dtPad(value.getUTCMinutes().toString());
+    const s = dtPad(value.getUTCSeconds().toString());
+    const ms = dtPad(value.getUTCMilliseconds().toString(), 3);
+    const fmtDate = `${value.getUTCFullYear()}-${m}-${d}T${h}:${min}:${s}.${ms}`;
+    return `${this._declaration(title)}${fmtDate}`;
+  }
+  _format(): string[] {
+    const rDeclaration = /(.*)\s=/;
+    const out = [];
+    for (let i = 0; i < this.output.length; i++) {
+      const l = this.output[i];
+      // we keep empty entry for array of objects
+      if (l[0] === "[" && l[1] !== "[") {
+        // empty object
+        if (this.output[i + 1] === "") {
+          i += 1;
+          continue;
+        }
+        out.push(l);
+      } else {
+        const m = rDeclaration.exec(l);
+        if (m) {
+          out.push(l.replace(m[1], pad(m[1], this.maxPad, { side: "right" })));
+        } else {
+          out.push(l);
+        }
+      }
+    }
+    // Cleaning multiple spaces
+    const cleanedOutput = [];
+    for (let i = 0; i < out.length; i++) {
+      const l = out[i];
+      if (!(l === "" && out[i + 1] === "")) {
+        cleanedOutput.push(l);
+      }
+    }
+    return cleanedOutput;
+  }
+}
+
+export function stringify(srcObj: object): string {
+  let out: string[] = [];
+  out = new Dumper(srcObj).dump();
+  return out.join("\n");
+}
+
 export function parse(tomlString: string): object {
   // File is potentially using EOL CRLF
   tomlString = tomlString.replace(/\r\n/g, "\n").replace(/\\\n/g, "\n");
diff --git a/toml/parser_test.ts b/toml/parser_test.ts
index 77bf9dc97..6cafb4b0d 100644
--- a/toml/parser_test.ts
+++ b/toml/parser_test.ts
@@ -1,7 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import { test } from "../testing/mod.ts";
 import { assertEquals } from "../testing/asserts.ts";
-import { parseFile } from "./parser.ts";
+import { parseFile, stringify } from "./parser.ts";
 import * as path from "../fs/path/mod.ts";
 const testFilesDir = path.resolve("toml", "testdata");
 
@@ -282,3 +282,97 @@ test({
     assertEquals(actual, expected);
   }
 });
+
+test({
+  name: "[TOML] Stringify",
+  fn() {
+    const src = {
+      foo: { bar: "deno" },
+      this: { is: { nested: "denonono" } },
+      arrayObjects: [{ stuff: "in" }, {}, { the: "array" }],
+      deno: "is",
+      not: "[node]",
+      regex: "<ic*s*>",
+      NANI: "何?!",
+      comment: "Comment inside # the comment",
+      int1: 99,
+      int2: 42,
+      int3: 0,
+      int4: -17,
+      int5: 1000,
+      int6: 5349221,
+      int7: 12345,
+      flt1: 1.0,
+      flt2: 3.1415,
+      flt3: -0.01,
+      flt4: 5e22,
+      flt5: 1e6,
+      flt6: -2e-2,
+      flt7: 6.626e-34,
+      odt1: new Date("1979-05-01T07:32:00Z"),
+      odt2: new Date("1979-05-27T00:32:00-07:00"),
+      odt3: new Date("1979-05-27T00:32:00.999999-07:00"),
+      odt4: new Date("1979-05-27 07:32:00Z"),
+      ld1: new Date("1979-05-27"),
+      reg: /foo[bar]/,
+      sf1: Infinity,
+      sf2: Infinity,
+      sf3: -Infinity,
+      sf4: NaN,
+      sf5: NaN,
+      sf6: NaN,
+      data: [["gamma", "delta"], [1, 2]],
+      hosts: ["alpha", "omega"]
+    };
+    const expected = `deno    = "is"
+not     = "[node]"
+regex   = "<ic*s*>"
+NANI    = "何?!"
+comment = "Comment inside # the comment"
+int1    = 99
+int2    = 42
+int3    = 0
+int4    = -17
+int5    = 1000
+int6    = 5349221
+int7    = 12345
+flt1    = 1
+flt2    = 3.1415
+flt3    = -0.01
+flt4    = 5e+22
+flt5    = 1000000
+flt6    = -0.02
+flt7    = 6.626e-34
+odt1    = 1979-05-01T07:32:00.000
+odt2    = 1979-05-27T07:32:00.000
+odt3    = 1979-05-27T07:32:00.999
+odt4    = 1979-05-27T07:32:00.000
+ld1     = 1979-05-27T00:00:00.000
+reg     = "/foo[bar]/"
+sf1     = inf
+sf2     = inf
+sf3     = -inf
+sf4     = NaN
+sf5     = NaN
+sf6     = NaN
+data    = [["gamma","delta"],[1,2]]
+hosts   = ["alpha","omega"]
+
+[foo]
+bar     = "deno"
+
+[this.is]
+nested  = "denonono"
+
+[[arrayObjects]]
+stuff   = "in"
+
+[[arrayObjects]]
+
+[[arrayObjects]]
+the     = "array"
+`;
+    const actual = stringify(src);
+    assertEquals(actual, expected);
+  }
+});