Add support for CSV data model

csv-parser.js

@@ -0,0 +1,95 @@
+"use strict";
+
+const CHAR_DOUBLE_QUOTE = 34;
+const CHAR_CR = 13;
+const CHAR_LF = 10;
+const CHAR_COMMA = 44;
+
+// https://tools.ietf.org/html/rfc4180#section-2
+function parseCsv(data) {
+  const rows = [];
+  let row = [];
+  let field = "";
+  let escapedState = false;
+  let i = 0;
+
+  function addField() {
+    row.push(field);
+    field = "";
+  }
+
+  function addRow() {
+    rows.push(row);
+    row = [];
+    // Ignore empty lines
+    while ([CHAR_LF, CHAR_CR].includes(data.charCodeAt(i + 1))) i++;
+  }
+
+  data = data.trim() + "\n";
+
+  for (i; i < data.length; i++) {
+    const char = data.charAt(i);
+    switch (data.charCodeAt(i)) {
+      case CHAR_DOUBLE_QUOTE:
+        if (!escapedState) {
+          // quoted field started
+          if (field.length) throw new Error("Invalid CSV format");
+          escapedState = true;
+        } else {
+          const nextChar = data.charCodeAt(i + 1);
+          if (nextChar === CHAR_DOUBLE_QUOTE) {
+            field += char;
+            i++;
+          } else if (nextChar && ![CHAR_COMMA, CHAR_CR, CHAR_LF].includes(nextChar)) {
+            throw new Error("Invalid CSV format");
+          } else {
+            // quoted field ended
+            escapedState = false;
+          }
+        }
+        break;
+
+      case CHAR_COMMA:
+        if (!escapedState) addField();
+        else field += char;
+        break;
+
+      case CHAR_CR:
+      case CHAR_LF:
+        if (!escapedState) {
+          addField();
+          addRow();
+        }
+        else {
+          field += char;
+        }
+        break;
+
+      default:
+        field += char;
+        break;
+    }
+  }
+
+  if (escapedState) throw new Error("Invalid CSV format");
+  return rows;
+}
+
+function reduce(rows, headerFirstRow = true) {
+  if (headerFirstRow) {
+    const headers = rows.shift();
+    return rows.map(row => {
+      let obj = {};
+      for (let i = 0; i < headers.length; i++)
+        obj[headers[i]] = row[i];
+      return obj;
+    });
+  } else {
+    return rows.map(row => {
+      return Object.assign({}, row);
+    });
+  }
+}
+
+exports.parseCsv = parseCsv;
+exports.reduce = reduce;