Merge pull request #1 from cbrittingham/maxLines-#275

Feature: add maxRows for C2FO#275
cbrittingham · Aug 27, 2019 · 0cc34c8 · 0cc34c8
2 parents 3deb16b + 9589054
commit 0cc34c8
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Showing 3 changed files with 14 additions and 1 deletion.
diff --git a/docs/parsing.md b/docs/parsing.md
@@ -46,6 +46,7 @@
 * `rtrim: {boolean} = false`: Set to `true` to right trim all fields.
 * `ltrim: {boolean} = false`: Set to `true` to left trim all fields.
 * `encoding: {string} = 'utf8'`: Passed to [StringDecoder](https://nodejs.org/api/string_decoder.html#string_decoder_new_stringdecoder_encoding) when decoding incoming buffers. Change if incoming content is not 'utf8' encoded.
+- `maxRows: {number}`: Up to the given number of rows will be returned if set to a number greater than 0 (e.g., `100` would return the first 100 rows of data).
 
 <a name="parsing-events"></a>
 ## Events

diff --git a/src/parser/ParserOptions.ts b/src/parser/ParserOptions.ts
@@ -15,6 +15,7 @@ export interface ParserOptionsArgs{
     ltrim?: boolean;
     rtrim?: boolean;
     encoding?: string;
+    maxRows?: number;
 }
 
 export class ParserOptions {
@@ -56,6 +57,10 @@ export class ParserOptions {
 
     public readonly encoding: string = 'utf8';
 
+    public readonly limitRows: boolean = false;
+
+    public readonly maxRows: number = -1;
+
     public constructor(opts?: ParserOptionsArgs) {
         Object.assign(this, opts || {});
         if (this.delimiter.length > 1) {
@@ -65,5 +70,9 @@ export class ParserOptions {
         this.escapeChar = isString(this.escape) ? this.escape : this.quote;
         this.supportsComments = !isNil(this.comment);
         this.NEXT_TOKEN_REGEXP = new RegExp(`([^\\s]|\\r\\n|\\n|\\r|${this.escapedDelimiter})`);
+
+        if (this.maxRows > 0) {
+            this.limitRows = true;
+        }
     }
 }
diff --git a/src/parser/parser/Parser.ts b/src/parser/parser/Parser.ts
@@ -69,9 +69,11 @@ export default class Parser {
         return { line: scanner.line, rows };
     }
 
+    private rowCount: number = 0;
+
     private parseRow(scanner: Scanner, rows: RowArray[]): boolean {
         const nextToken = scanner.nextNonSpaceToken;
-        if (!nextToken) {
+        if (!nextToken || (this.parserOptions.limitRows && this.rowCount >= this.parserOptions.maxRows)) {
             return false;
         }
         const row = this.rowParser.parse(scanner);
@@ -82,6 +84,7 @@ export default class Parser {
             return true;
         }
         rows.push(row);
+        this.rowCount += 1;
         return true;
     }
 }