基于层次注意力机制的源代码迁移模型

本文构建了一种基于层次注意力机制的源代码迁移模型（Hierarchical Pointer-Generator Networks，HPGN）。其在迁移过程中通过关注代码语句的语法和语义，从而进一步提升迁移代码的语义一致性。

本文已被《计算机应用研究录用》录用，计划2023年10月至11月发表
论文名：基于层次注意力机制的源代码迁移模型
作者：李征 徐明瑞 吴永豪 刘勇 陈翔 武淑美 刘恒源
论文发表后更新引用格式

HPGN模型架构：

残差状态传递机制：

门控状态传递机制：

目前正在调整项目结构，部分代码正在更改中

HPGN
│  hpgn_main.py                  层次指针生成网络——训练
│  metric_result_analysis.py     指标分析
│  pgn_main.py                   指针生成网络——训练
│  readme.md
├─dataset
│  └─Csharp_Java      数据、模型、分词器、参考输出
│      ├─dataset        预处理数据集和单词表
│      ├─model          模型以及输出样例
│      ├─trained-model  本实验模型的输出样例
│      └─Tokenizers     分词器
├─transformer_result    transformer输出结果
├─evaluator         bleu、Codebleu
│  └─CodeBLEU
└─Network           指针生成网络、层次指针生成网络
  

运行环境

python=3.9
tensorflow=2.7

评测指标 与 数据集

• BLEU：计算生成的序列和参考序列的n-gram重叠率，并返回0到100%之间的分值。BLEU值越高，表示生成的序列越接近参考序列
• 精确匹配（Exact Match，EM）：评测预测输出和参考输出是否完全一致
• CodeBLEU：采用BLEU的n-gram匹配算法，并通过代码解析工具引入了抽象语法树和数据流匹配算法。CodeBLEU根据代码的文本、语法和语义来评估代码，给出0到100%之间的分数。CodeBLEU值越高，代码生成的质量越高

数据集：基于真实项目的(Java-C#)数据集CodeTrans

实验结果

HPGN 隐藏层-64维，网络-1层

Java到C#

模型	BLEU	EM	CodeBLEU
Naive	18.54	0.0	-
PBSMT	43.53	12.5	42.71
tree-to-tree	36.34	3.4	42.13
Transformer	58.53	34.4	64.20
Resnet-HPGN	58.74	19.5	63.08
Gate-HPGN	61.40	27.3	64.93
Base-HPGN	59.79	20.7	63.88
指针生成网络	26.18	13.8	43.87

C#到Java

模型	BLEU	EM	CodeBLEU
Naive	18.69	0.0	-
PBSMT	40.06	16.1	43.48
tree-to-tree	32.09	4.4	43.86
Transformer	52.87	34.7	58.56
Resnet-HPGN	60.28	29.5	64.20
Gate-HPGN	60.95	32.1	64.62
Base-HPGN	58.26	30.0	62.35
指针生成网络	27.84	20.5	44.88

人工评分

指标

分值	评价指标
	语法	语义
5	没有语法错误	语义一致
4	存在少数语法错误	少数语义缺失
3	存在部分语法错误	部分语义缺失或存在少数无关语义
2	存在大量语法错误	大量语义缺失或存在部分无关语义
1	不能看出语法结构	语义完全无关

成绩

模型		Java到C#		C#到Java
		语法	语义	语法	语义
Gate-HPGN	1	4.44	4.47	4.49	4.49
	2	4.16	4.47	4.07	4.38
	3	4.66	4.68	4.73	4.74
	4	4.30	4.34	4.67	4.54
	5	4.45	4.50	4.62	4.53
	平均	4.40	4.49	4.52	4.54
Transformer	1	4.64	4.21	4.73	4.29
	2	4.28	4.14	4.22	4.16
	3	4.79	4.67	4.83	4.69
	4	4.44	4.12	4.78	4.37
	5	4.64	4.45	4.79	4.35
	平均	4.56	4.32	4.67	4.37

输出案例

与对比模型对比的案例研究

样例1
源代码	public static final WeightedTerm[] getTerms(Query query){return getTerms(query,false);}
参考代码	public static WeightedTerm[] GetTerms(Query query){return GetTerms(query, false);}
tree-to-tree	public static WeightedTerm[] identifier(Query query) { return capacity(query, false); }
Transformer	public static WeightedTerm[] GetTerms(Query queryTerm) { return GetTerms(query, queryTerms, Term); }
Gate-HPGN	public static WeightedTerm[] GetTerms(Query query)) { return GetTerms(query,false); }

样例2
源代码	public long skip(long n){int s = (int) Math.min(available(), Math.max(0, n));ptr += s;return s;}
参考代码	public override long Skip(long n){int s = (int)Math.Min(Available(), Math.Max(0, n)); ptr += s;return s;}
tree-to-tree	public override long skip(long n) { int s = (int) Math.Min(0, n); ptr += n; return s; }
Transformer	public override long Skip(long n) { int s = (int)(MIN_SHIFT); return ((long)((ulong)block >> shift)) & unchecked((int)(0xff)); }
Gate-HPGN	public virtual long skip(long n) { int s = (int)(offsetmin(available(), Math.max(0, n)); ptr += s; return s; }

与消融实验模型对比的案例研究

样例3
源代码	public final boolean hasPassedThroughNonGreedyDecision() { return passedThroughNonGreedyDecision; }
参考代码	public bool hasPassedThroughNonGreedyDecision() { return passedThroughNonGreedyDecision; }
Resnet-HPGN	public bool H hasPassedThroughNonGreedyDecision() { return passedThroughNonGreedyDecision; }
Gate-HPGN	public bool hasPassedThroughNonGreedyDecision() { return passedThroughNonGreedyDecision; }
Base-HPGN	public bool HPasassedThroughNonGreedyDecision() { return passedThroughNonGreedyDecision; }
指针生成网络	public virtual bool hasPassedThroughNonGreedyDecision() { return passedroughNonGreedyDecision; } } } } } } } } } } }

样例4
源代码	public UpdateUserRequest(String userName) { setUserName(userName); }
参考代码	public UpdateUserRequest(string userName) { _userName = userName; }
Resnet-HPGN	public UpdateUserRequest(string userName) { _userName =NameName; }
Gate-HPGN	public UpdateUserRequest(string userName) { _userName = userName; }
Base-HPGN	public UpdateUserRequest(string userName) { _userName = groupName; }
指针生成网络	public UpdateUserRequest(string userName) { _UserNameuserName); }

与代码迁移工具对比的案例研究

样例5
源代码	public LatvianStemFilterFactory(Map args) { super(args);     if (!args.isEmpty()) { throw new IllegalArgumentException("Unknown parameters: " + args); } }
参考代码	public LatvianStemFilterFactory(IDictionary args): base(args) {     if (args.Count > 0) { throw new System.ArgumentException("Unknown parameters: " + args); } }
代码迁移工具	using System.Collections.Generic; //JAVA TO C# CONVERTER WARNING: The following constructor is declared outside of its associated class: //ORIGINAL LINE: public LatvianStemFilterFactory(Map args) public LatvianStemFilterFactory(IDictionary args) : base(args) {     if (args.Count > 0) {throw new System.ArgumentException("Unknown parameters: " + args);} }
Gate-HPGN	public LatvianStemFilterFactory(IDictionary args): base(args) {     if (args.Count > 0) {throw new System.ArgumentException("Unknown parameters: " + args);} }

样例6
源代码	public PutIntegrationResult putIntegration(PutIntegrationRequest request) {     request = beforeClientExecution(request);     return executePutIntegration(request); }
参考代码	public virtual PutIntegrationResponse PutIntegration(PutIntegrationRequest request) {     var options = new InvokeOptions();     options.RequestMarshaller = PutIntegrationRequestMarshaller.Instance;     options.ResponseUnmarshaller = PutIntegrationResponseUnmarshaller.Instance;     return Invoke(request, options); }
代码迁移工具	public virtual PutIntegrationResult putIntegration(PutIntegrationRequest request) {     request = beforeClientExecution(request);     return executePutIntegration(request); }
Gate-HPGN	public virtual PutIntegrationResponse PutIntegration(PutIntegrationRequest request) {     var options = new InvokeOptions();     options.RequestMarshaller = PutIntegrationRequestMarshaller.Instance;     options.ResponseUnmarshaller = PutIntegrationResponseUnmarshaller.Instance;     return Invoke(request, options); }

HPGN的错误输出案例研究

错误：不符合EM指标评价方法的代码

样例7
源代码	public boolean remove(Object o) { synchronized (mutex) { return delegate().remove(o); } }
参考代码	public virtual bool remove(object @object) { lock (mutex) { return c.remove(@object); } }
Gate-HPGN	public override bool Remove(object o) { lock (mutex) { return } }

样例8
源代码	public static String toHex(long value) { StringBuilder sb = new StringBuilder(16); writeHex(sb, value, 16, "");     return sb.toString(); }
参考代码	public static string ToHex(int value) { return ToHex((long)value, 8); }
Gate-HPGN	public static string ToHex(long value) { StringBuilder sb = new StringBuilder(16); writeHex(sb, value, 16, ""); return sb.ToString(); }