1 files changed, 251 insertions, 0 deletions
diff --git a/std/encoding/csv.ts b/std/encoding/csv.ts
new file mode 100644
index 000000000..10d72a8a5
--- /dev/null
+++ b/std/encoding/csv.ts
@@ -0,0 +1,251 @@
+// 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 } from "../io/bufio.ts";
+import { TextProtoReader } from "../textproto/mod.ts";
+import { StringReader } from "../io/readers.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;
+  }
+}
+
+/**
+ * @property comma - Character which separates values. Default: ','
+ * @property comment - Character to start a comment. Default: '#'
+ * @property trimLeadingSpace - Flag to trim the leading space of the value.
+ *           Default: 'false'
+ * @property lazyQuotes - Allow unquoted quote in a quoted field or non double
+ *           quoted quotes in quoted field Default: 'false'
+ * @property fieldsPerRecord - Enabling the check of fields for each row.
+ *           If == 0, first row is used as referal for the number of fields.
+ */
+export interface ParseOptions {
+  comma?: string;
+  comment?: string;
+  trimLeadingSpace?: boolean;
+  lazyQuotes?: boolean;
+  fieldsPerRecord?: number;
+}
+
+function chkOptions(opt: ParseOptions): void {
+  if (!opt.comma) opt.comma = ",";
+  if (!opt.trimLeadingSpace) opt.trimLeadingSpace = false;
+  if (
+    INVALID_RUNE.includes(opt.comma!) ||
+    INVALID_RUNE.includes(opt.comment!) ||
+    opt.comma === opt.comment
+  ) {
+    throw new Error("Invalid Delimiter");
+  }
+}
+
+async function read(
+  Startline: number,
+  reader: BufReader,
+  opt: ParseOptions = { comma: ",", trimLeadingSpace: false }
+): Promise<string[] | Deno.EOF> {
+  const tp = new TextProtoReader(reader);
+  let line: string;
+  let result: string[] = [];
+  const lineIndex = Startline;
+
+  const r = await tp.readLine();
+  if (r === Deno.EOF) return Deno.EOF;
+  line = r;
+  // 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 [];
+  }
+
+  // line starting with comment character is ignored
+  if (opt.comment && trimmedLine[0] === opt.comment) {
+    return [];
+  }
+
+  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) {
+    throw new ParseError(Startline, lineIndex, 'bare " in non-quoted-field');
+  }
+  return result;
+}
+
+export async function readAll(
+  reader: BufReader,
+  opt: ParseOptions = {
+    comma: ",",
+    trimLeadingSpace: false,
+    lazyQuotes: false
+  }
+): Promise<string[][]> {
+  const result: string[][] = [];
+  let _nbFields: number;
+  let lineResult: string[];
+  let first = true;
+  let lineIndex = 0;
+  chkOptions(opt);
+
+  for (;;) {
+    const r = await read(lineIndex, reader, opt);
+    if (r === Deno.EOF) break;
+    lineResult = r;
+    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) {
+        throw new ParseError(lineIndex, lineIndex, "wrong number of fields");
+      }
+      result.push(lineResult);
+    }
+  }
+  return result;
+}
+
+/**
+ * HeaderOption provides the column definition
+ * and the parse function for each entry of the
+ * column.
+ */
+export interface HeaderOption {
+  name: string;
+  parse?: (input: string) => unknown;
+}
+
+export interface ExtendedParseOptions extends ParseOptions {
+  header: boolean | string[] | HeaderOption[];
+  parse?: (input: unknown) => unknown;
+}
+
+/**
+ * Csv parse helper to manipulate data.
+ * Provides an auto/custom mapper for columns and parse function
+ * for columns and rows.
+ * @param input Input to parse. Can be a string or BufReader.
+ * @param opt options of the parser.
+ * @param [opt.header=false] HeaderOptions
+ * @param [opt.parse=null] Parse function for rows.
+ * Example:
+ *     const r = await parseFile('a,b,c\ne,f,g\n', {
+ *      header: ["this", "is", "sparta"],
+ *       parse: (e: Record<string, unknown>) => {
+ *         return { super: e.this, street: e.is, fighter: e.sparta };
+ *       }
+ *     });
+ * // output
+ * [
+ *   { super: "a", street: "b", fighter: "c" },
+ *   { super: "e", street: "f", fighter: "g" }
+ * ]
+ */
+export async function parse(
+  input: string | BufReader,
+  opt: ExtendedParseOptions = {
+    header: false
+  }
+): Promise<unknown[]> {
+  let r: string[][];
+  if (input instanceof BufReader) {
+    r = await readAll(input, opt);
+  } else {
+    r = await readAll(new BufReader(new StringReader(input)), opt);
+  }
+  if (opt.header) {
+    let headers: HeaderOption[] = [];
+    let i = 0;
+    if (Array.isArray(opt.header)) {
+      if (typeof opt.header[0] !== "string") {
+        headers = opt.header as HeaderOption[];
+      } else {
+        const h = opt.header as string[];
+        headers = h.map(
+          (e): HeaderOption => {
+            return {
+              name: e
+            };
+          }
+        );
+      }
+    } else {
+      headers = r.shift()!.map(
+        (e): HeaderOption => {
+          return {
+            name: e
+          };
+        }
+      );
+      i++;
+    }
+    return r.map((e): unknown => {
+      if (e.length !== headers.length) {
+        throw `Error number of fields line:${i}`;
+      }
+      i++;
+      const out: Record<string, unknown> = {};
+      for (let j = 0; j < e.length; j++) {
+        const h = headers[j];
+        if (h.parse) {
+          out[h.name] = h.parse(e[j]);
+        } else {
+          out[h.name] = e[j];
+        }
+      }
+      if (opt.parse) {
+        return opt.parse(out);
+      }
+      return out;
+    });
+  }
+  if (opt.parse) {
+    return r.map((e: string[]): unknown => opt.parse!(e));
+  }
+  return r;
+}