BatchFilter.java

package com.hubspot.jinjava.lib.filter;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.apache.commons.lang3.math.NumberUtils;

import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
import com.hubspot.jinjava.doc.annotations.JinjavaParam;
import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
import com.hubspot.jinjava.interpret.JinjavaInterpreter;
import com.hubspot.jinjava.util.ForLoop;
import com.hubspot.jinjava.util.ObjectIterator;

@JinjavaDoc(
    value = "A filter that groups up items within a sequence",
    params = {
        @JinjavaParam(value = "value", desc = "The sequence or dict that the filter is applied to"),
        @JinjavaParam(value = "linecount", type = "number", desc = "Number of items to include in the batch", defaultValue = "0"),
        @JinjavaParam(value = "fill_with", desc = "Value used to fill up missing items")
    },
    snippets = {
        @JinjavaSnippet(
            code = "{% set items=[1, 2, 3, 4, 5] %}\n\n" +
                "<table>\n" +
                "{% for row in items|batch(3, ' ') %}\n" +
                "  <tr>\n" +
                "  {%- for column in row %}\n" +
                "    <td>{{ column }}</td>\n" +
                "  {%- endfor %}\n" +
                "  </tr>\n" +
                "{% endfor %}\n" +
                "</table>",
            output = "<table>\n" +
                "  <tr>\n" +
                "    <td>1</td>\n" +
                "    <td>2</td>\n" +
                "    <td>3</td>\n" +
                "  </tr>\n" +
                "  <tr>\n" +
                "    <td>4</td>\n" +
                "    <td>5</td>\n" +
                "    <td> </td>\n" +
                "  </tr>\n" +
                "</table>")
    })
public class BatchFilter implements Filter {

  @Override
  public String getName() {
    return "batch";
  }

  @Override
  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
    if (var == null || args.length == 0) {
      return Collections.emptyList();
    }

    int lineCount = NumberUtils.toInt(args[0], 0);
    if (lineCount == 0) {
      return Collections.emptyList();
    }

    Object fillWith = args.length > 1 ? args[1] : null;

    ForLoop loop = ObjectIterator.getLoop(var);
    List<List<Object>> result = new ArrayList<>();
    List<Object> currentRow = null;

    while (loop.hasNext()) {
      Object item = loop.next();

      if (currentRow == null) {
        currentRow = new ArrayList<>();
        result.add(currentRow);
      }

      currentRow.add(item);

      if (currentRow.size() == lineCount) {
        currentRow = null;
      }
    }

    if (currentRow != null) {
      while (currentRow.size() < lineCount) {
        currentRow.add(fillWith);
      }
    }

    return result;
  }

}