Add encoding/csv (denoland/deno_std#432)

Original: c8a7dcdcd0

encoding/csv.ts

@@ -0,0 +1,151 @@
+// Ported from Go:
+// https://github.com/golang/go/blob/go1.12.5/src/encoding/csv/
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { BufReader, BufState } from "../io/bufio.ts";
+import { TextProtoReader } from "../textproto/mod.ts";
+
+const INVALID_RUNE = ["\r", "\n", '"'];
+
+export class ParseError extends Error {
+  StartLine: number;
+  Line: number;
+  constructor(start: number, line: number, message: string) {
+    super(message);
+    this.StartLine = start;
+    this.Line = line;
+  }
+}
+
+export interface ParseOptions {
+  comma: string;
+  comment?: string;
+  trimLeadingSpace: boolean;
+  lazyQuotes?: boolean;
+  fieldsPerRecord?: number;
+}
+
+function chkOptions(opt: ParseOptions): Error | null {
+  if (
+    INVALID_RUNE.includes(opt.comma) ||
+    INVALID_RUNE.includes(opt.comment) ||
+    opt.comma === opt.comment
+  ) {
+    return Error("Invalid Delimiter");
+  }
+  return null;
+}
+
+export async function read(
+  Startline: number,
+  reader: BufReader,
+  opt: ParseOptions = { comma: ",", comment: "#", trimLeadingSpace: false }
+): Promise<[string[], BufState]> {
+  const tp = new TextProtoReader(reader);
+  let err: BufState;
+  let line: string;
+  let result: string[] = [];
+  let lineIndex = Startline;
+
+  [line, err] = await tp.readLine();
+
+  // Normalize \r\n to \n on all input lines.
+  if (
+    line.length >= 2 &&
+    line[line.length - 2] === "\r" &&
+    line[line.length - 1] === "\n"
+  ) {
+    line = line.substring(0, line.length - 2);
+    line = line + "\n";
+  }
+
+  const trimmedLine = line.trimLeft();
+  if (trimmedLine.length === 0) {
+    return [[], err];
+  }
+
+  // line starting with comment character is ignored
+  if (opt.comment && trimmedLine[0] === opt.comment) {
+    return [result, err];
+  }
+
+  result = line.split(opt.comma);
+
+  let quoteError = false;
+  result = result.map(
+    (r): string => {
+      if (opt.trimLeadingSpace) {
+        r = r.trimLeft();
+      }
+      if (r[0] === '"' && r[r.length - 1] === '"') {
+        r = r.substring(1, r.length - 1);
+      } else if (r[0] === '"') {
+        r = r.substring(1, r.length);
+      }
+
+      if (!opt.lazyQuotes) {
+        if (r[0] !== '"' && r.indexOf('"') !== -1) {
+          quoteError = true;
+        }
+      }
+      return r;
+    }
+  );
+  if (quoteError) {
+    return [
+      [],
+      new ParseError(Startline, lineIndex, 'bare " in non-quoted-field')
+    ];
+  }
+  return [result, err];
+}
+
+export async function readAll(
+  reader: BufReader,
+  opt: ParseOptions = {
+    comma: ",",
+    trimLeadingSpace: false,
+    lazyQuotes: false
+  }
+): Promise<[string[][], BufState]> {
+  const result: string[][] = [];
+  let _nbFields: number;
+  let err: BufState;
+  let lineResult: string[];
+  let first = true;
+  let lineIndex = 0;
+  err = chkOptions(opt);
+  if (err) return [result, err];
+
+  for (;;) {
+    [lineResult, err] = await read(lineIndex, reader, opt);
+    if (err) break;
+    lineIndex++;
+    // If fieldsPerRecord is 0, Read sets it to
+    // the number of fields in the first record
+    if (first) {
+      first = false;
+      if (opt.fieldsPerRecord !== undefined) {
+        if (opt.fieldsPerRecord === 0) {
+          _nbFields = lineResult.length;
+        } else {
+          _nbFields = opt.fieldsPerRecord;
+        }
+      }
+    }
+
+    if (lineResult.length > 0) {
+      if (_nbFields && _nbFields !== lineResult.length) {
+        return [
+          null,
+          new ParseError(lineIndex, lineIndex, "wrong number of fields")
+        ];
+      }
+      result.push(lineResult);
+    }
+  }
+  if (err !== "EOF") {
+    return [result, err];
+  }
+  return [result, null];
+}