Template.java

package com.antbrains.crf;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Template implements Serializable {
  private static final long serialVersionUID = 8936075816725599450L;
  public static final String[] BOS = { "_B-1", "_B-2", "_B-3", "_B-4" };
  public static final String[] EOS = { "_B+1", "_B+2", "_B+3", "_B+4" };
  private String[] patterns;

  public Template(String[] patterns) {
    this.patterns = patterns;
  }

  public Template(String templateFilename, String charset) throws IOException {
    BufferedReader br = null;
    List<String> patternList = new ArrayList<String>();
    try {
      br = new BufferedReader(new InputStreamReader(new FileInputStream(templateFilename), charset));
      String line;
      while ((line = br.readLine()) != null) {
        line = line.trim();
        if (line.length() == 0 || line.startsWith("#")) {
          continue;
        }
        patternList.add(line);
      }
    } finally {
      if (br != null) {
        br.close();
      }
    }
    this.patterns = patternList.toArray(new String[patternList.size()]);
  }

  public String[] getPatterns() {
    return patterns;
  }

  public void setPatterns(String[] patterns) {
    this.patterns = patterns;
  }

  private String expandPattern(String pattern, int itemIndex, List<String> attributes, int rowSize) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < pattern.length(); i++) {
      char c = pattern.charAt(i);
      switch (c) {
      case '%':
        i++;
        if (i >= pattern.length()) {
          throw new IllegalStateException("template error: " + pattern);
        }
        char nextChar = pattern.charAt(i);
        switch (nextChar) {
        case 'x':
          i++;
          i = getIndex(sb, pattern, i, itemIndex, attributes, rowSize);
          break;
        default:
          throw new IllegalStateException("template error: " + pattern);
        }
        break;
      default:
        sb.append(c);
      }
    }
    return sb.toString();
  }

  private int getIndex(StringBuilder sb, String template, int index, int pos,
      List<String> attributes, int rowSize) {
    char firstChar = template.charAt(index++);
    if (firstChar != '[') {
      throw new IllegalStateException("template error: " + template);
    }
    int col = 0, row = 0;
    int neg = 1;
    if (template.charAt(index++) == '-') {
      neg = -1;
    } else {
      index--;
    }

    NEXT_ROW: for (; index < template.length(); index++) {
      char c = template.charAt(index);
      switch (c) {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        row = row * 10 + (c - '0');
        break;
      case ',':
        index++;
        break NEXT_ROW;
      default:
        throw new IllegalStateException("wrong template format: " + template);
      }
    }

    NEXT_COLUMN: for (; index < template.length(); index++) {
      char c = template.charAt(index);
      switch (c) {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        col = col * 10 + (c - '0');
        break;
      case ']':
        break NEXT_COLUMN;
      default:
        throw new IllegalStateException("template error: " + template);
      }
    }

    row *= neg;

    int itemNum = attributes.size() / rowSize;
    int idx = pos + row;
    if (idx < 0) {
      sb.append(BOS[-idx - 1]);
    } else if (idx >= itemNum) {
      sb.append(EOS[idx - itemNum]);
    } else {
      sb.append(attributes.get(idx * rowSize + col));
    }
    return index;
  }

  public List<String> expandTemplate(List<String> attributes, int itemNum) {
    if (attributes == null) {
      return Collections.emptyList();
    }
    int rowSize = attributes.size() / itemNum;
    List<String> expandedAttributes = new ArrayList<String>(itemNum * length());
    for (int itemIndex = 0; itemIndex < itemNum; itemIndex++) {
      for (int patternIndex = 0; patternIndex < length(); patternIndex++) {
        expandedAttributes
            .add(expandPattern(patterns[patternIndex], itemIndex, attributes, rowSize));
      }
    }
    return expandedAttributes;
  }

  public int length() {
    return patterns.length;
  }

  public int size() {
    return patterns.length;
  }
}