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This is a utils library for java 8 project. It include parsec combinators and sql generators library.
There is a newer version: 2.9.2
package jaskell.parsec.common;

import static jaskell.parsec.common.Atom.one;
import static jaskell.parsec.common.Atom.pack;
import static jaskell.parsec.common.Combinator.attempt;
import static jaskell.parsec.common.Combinator.choice;
import static jaskell.parsec.common.Txt.newline;
import static jaskell.parsec.common.Txt.text;

import jaskell.parsec.Neighborhood;
import jaskell.parsec.ParsecException;

import java.io.EOFException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

/**
 * Created by Mars Liu on 2016-01-02.
 * TxtState 类型提供一个基本的 state 实现,它将文本转为字符状态，并提供行号查询支持
 * 如果我们要处理的数据量不至于对内存使用造成负担,也没有并发安全的需要,可以使用它.
 */
public class TxtState implements State {
  private final List buffer;
  private final String content;
  private final Map lines = new HashMap<>();
  private int current = 0;
  private int tran = -1;

  @Override
  public Character next() throws EOFException {
    if (this.current >= this.buffer.size()) {
      throw new EOFException();
    }
    Character re = this.buffer.get(this.current);
    this.current++;
    return re;
  }

  @Override
  public Integer status() {
    return this.current;
  }

  @Override
  public Integer begin() {
    if (this.tran == -1) {
      this.tran = this.current;
    }
    return this.current;
  }

  @Override
  public Integer begin(Integer tran) {
    if (this.tran > tran) {
      this.tran = tran;
    }
    return this.tran;
  }

  @Override
  public void rollback(Integer tran) {
    if (this.tran == tran) {
      this.tran = -1;
    }
    this.current = tran;
  }

  @Override
  public void commit(Integer tran) {
    if (this.tran == tran) {
      this.tran = -1;
    }
  }

  @Override
  public ParsecException trap(String message) {
    return new ParsecException(this.current, message);
  }

  public TxtState(String content, String newLine) {
    this.content = content;
    List characters = new ArrayList<>();
    for (char c : content.toCharArray()) {
      characters.add(c);
    }
    SimpleState state = new SimpleState<>(characters);
    Parsec chr = choice(attempt(text(newLine).then(pack('\n'))), one());
    List buffer = new ArrayList<>();
    int last = 0;
    while (true) {
      try {
        Character re = chr.parse(state);
        if (re == '\n') {
          lines.put(last, state.status());
          lines.put(last + 1, last + 1);
          last = state.status();
        }
        buffer.add(re);
      } catch (EOFException error) {
        break;
      }
    }
    this.buffer = buffer;
  }

  public TxtState(String content) {
    this(content, "\n");
  }

  public int lineOfIndex(int index) {
    int i = 0;
    for (int idx : lines.keySet()) {
      if (idx <= index && index <= lines.get(idx)) {
        return i;
      }
      i += 1;
    }
    return -1;
  }

  public Neighborhood neighborhood() {
    return neighborhood(current);
  }

  public Neighborhood neighborhood(int index) {
    int top = Math.min(index + 10, content.length());
    int bottom = Math.max(index - 10, 0);
    Neighborhood result = new Neighborhood();
    result.setTop(top);
    result.setBottom(bottom);
    result.setContent(content.substring(bottom, top));
    return result;
  }
}