IndentFilter.java

package com.hubspot.jinjava.lib.filter;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

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

import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
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;

@JinjavaDoc(
    value = "Uses whitespace to indent a string.",
    params = {
        @JinjavaParam(value = "s", desc = "The string to indent"),
        @JinjavaParam(value = "width", type = "number", defaultValue = "4", desc = "Amount of whitespace to indent"),
        @JinjavaParam(value = "indentfirst", type = "boolean", defaultValue = "False", desc = "If True, first line will be indented")
    },
    snippets = {
        @JinjavaSnippet(desc = "Since HubSpot's compiler automatically strips whitespace, this filter will only work in tags where whitespace is retained, such as a <pre>",
            code = "<pre>\n" +
                "    {% set var = \"string to indent\" %}\n" +
                "    {{ var|indent(2, true) }}\n" +
                "</pre>")
    })
public class IndentFilter implements Filter {

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

  @Override
  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
    int width = 4;
    if (args.length > 0) {
      width = NumberUtils.toInt(args[0], 4);
    }

    boolean indentFirst = false;
    if (args.length > 1) {
      indentFirst = BooleanUtils.toBoolean(args[1]);
    }

    List<String> indentedLines = new ArrayList<>();
    for (String line : NEWLINE_SPLITTER.split(Objects.toString(var, ""))) {
      int thisWidth = indentedLines.size() == 0 && !indentFirst ? 0 : width;
      indentedLines.add(StringUtils.repeat(' ', thisWidth) + line);
    }

    return NEWLINE_JOINER.join(indentedLines);
  }

  private static final Splitter NEWLINE_SPLITTER = Splitter.on('\n');
  private static final Joiner NEWLINE_JOINER = Joiner.on('\n');

}