package io.github.wycst.wast.common.template;
import io.github.wycst.wast.common.compiler.JDKCompiler;
import io.github.wycst.wast.common.compiler.JavaSourceObject;
import io.github.wycst.wast.common.exceptions.ParserException;
import io.github.wycst.wast.common.utils.RegexUtils;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicLong;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* 字符串模板引擎
* 参考jsp模板引擎
*
* <% java代码；%>
* <%=java表达式%>
* ${k} el表达式解析
*
*
当前仅仅内部orm进行代码自动生成模块使用，性能未做优化
*
* @Author: wangy
* @Date: 2021/9/7 21:53
* @Description:
*/
public final class StringTemplate {
private static final AtomicLong ATOMIC_LONG = new AtomicLong(0);
private static final String PACKAGE_NAME = StringTemplate.class.getPackage().getName();
private static final String DEFINE_PREFIX = "$define ";
private static final String FOR_LOOP_REGEX = "^[$]for[ ]*[(][ ]*(\\w+)(,[ ]*(\\w+))?[ ]*[)][ ]*in[ ]*(\\w+)$";
private static final String IF_REGEX = "^[$]if[ ]*[(](.*?)[)]$";
private static final String ELSE_IF_REGEX = "^[$]else[ ]+if[ ]*[(](.*?)[)]$";
private static final String ELSE_REGEX = "^[$]else$";
private static final String PLACEHOLDER_REGEX = ".*[^\\\\]?[$][{]([ ]*[0-9a-zA-Z_.$]+[ ]*)[}].*";
private static final Pattern FOR_LOOP_PATTERN = Pattern.compile(FOR_LOOP_REGEX);
private static final Pattern IF_PATTERN = Pattern.compile(IF_REGEX);
private static final Pattern ELSE_IF_PATTERN = Pattern.compile(ELSE_IF_REGEX);
private static final Pattern ELSE_PATTERN = Pattern.compile(ELSE_REGEX);
private final String templateId = UUID.randomUUID().toString();
private final byte[] templateJavaSource;
private TemplateClass templateClass;
// 静态字符串临时缓冲区（优化）
private StringBuilder staticTempBuffer = new StringBuilder();
private boolean nextNewLine = false;
public StringTemplate(String template) {
StringBuilder importPackages = new StringBuilder();
importPackages.append("package " + PACKAGE_NAME + ";\r\n");
importPackages.append("import java.util.*;\r\n");
// importPackages.append("import io.github.wycst.wast.common.template.TemplateClass;\r\n");
// importPackages.append("import io.github.wycst.wast.common.utils.*;\r\n");
// 源代码
StringBuilder source = new StringBuilder();
String[] lines = template.split("\r\n", -1);
boolean javaCodeBegin = false;
boolean userLocalContext = false;
boolean defineLocalContext = false;
int scopeLevel = 0;
int flag = 0;
int index = 0, lineLength = lines.length;
for (String line : lines) {
index++;
if (nextNewLine) {
nextNewLine = false;
// 如果以占位符号结尾，追加换行符
appendIndent(source, scopeLevel);
source.append("\t\tprintln();\r\n");
} else {
if (line.length() == 0) {
boolean hasAppendNewLine = staticTempBuffer.length() > 0;
this.persistBuffer(source);
// 如果最后一个line为空忽略掉（分割虚拟出的一行）
if (index < lineLength || !hasAppendNewLine) {
appendIndent(source, scopeLevel);
source.append("\t\tprintln();\r\n");
}
continue;
}
}
// 转义符替换
line = line.replace("\\", "\\\\");
line = line.replace("\r", "\\r");
line = line.replace("\n", "\\n");
String trimLine = line.trim();
if (trimLine.startsWith("<%")) {
if (trimLine.endsWith("%>")) {
// java代码同一行
String lineCode = trimLine.substring(2, trimLine.length() - 2);
if (lineCode.startsWith("=")) {
// 解析表达式直接作为java代码执行
source.append("\t\tprintln(\"" + lineCode.substring(1).replace("\"", "\\\"") + "\");\r\n");
} else {
if (lineCode.startsWith("import ") && lineCode.endsWith(";")) {
importPackages.append(lineCode).append("\r\n");
} else {
// java代码
source.append("\t\t").append(lineCode).append("\r\n");
}
}
} else {
// java代码开始
javaCodeBegin = true;
}
} else if (trimLine.endsWith("%>")) {
// java代码结束
javaCodeBegin = false;
} else {
if (javaCodeBegin) {
// import语句
if (trimLine.startsWith("import ") && trimLine.endsWith(";")) {
importPackages.append(line);
} else {
source.append("\t\t").append(line).append("\r\n");
}
} else {
boolean isTextLine = true;
if (trimLine.startsWith("$")) {
isTextLine = false;
if (trimLine.matches(FOR_LOOP_REGEX)) {
persistBuffer(source);
if (!defineLocalContext) {
appendDefineSource(source, line, "Map localContext = null;");
appendDefineSource(source, line, "Iterable iterable = null;");
appendDefineSource(source, line, "int index = 0;");
defineLocalContext = true;
}
userLocalContext = appendForLoopSource(source, line, trimLine);
flag += 1;
scopeLevel++;
} else if (trimLine.startsWith(DEFINE_PREFIX)) {
this.persistBuffer(source);
appendIndent(source, scopeLevel);
appendDefineSource(source, line, trimLine);
} else if (trimLine.matches(IF_REGEX)) {
this.persistBuffer(source);
appendIndent(source, scopeLevel);
appendIfClauseSource(source, line, trimLine);
flag += 1;
scopeLevel++;
} else if (trimLine.matches(ELSE_IF_REGEX)) {
this.persistBuffer(source);
appendElseIfClauseSource(source, line, trimLine);
flag += 1;
} else if (trimLine.matches(ELSE_REGEX)) {
this.persistBuffer(source);
appendElseClauseSource(source, line, trimLine);
flag += 1;
} else if (trimLine.equals("$end")) {
this.persistBuffer(source);
if (scopeLevel > 0) {
scopeLevel--;
}
appendIndent(source, scopeLevel);
source.append("\t\t}\r\n");
flag -= 1;
} else {
// println
isTextLine = true;
}
if (flag == 0) {
userLocalContext = false;
if (scopeLevel > 0) {
scopeLevel--;
}
}
}
if (isTextLine) {
if (line.matches(PLACEHOLDER_REGEX)) {
this.persistBuffer(source);
line = line.replace("\"", "\\\"");
appendIndent(source, scopeLevel);
appendPlaceHolderLine(source, line, userLocalContext ? "localContext" : "context", scopeLevel);
// if (userLocalContext) {
// source.append("\t\tprintln(\"" + line + "\", localContext);\r\n");
// } else {
// source.append("\t\tprintln(\"" + line + "\", context);\r\n");
// }
} else {
// appendIndent(source, scopeLevel);
if (staticTempBuffer.length() == 0) {
appendIndent(source, scopeLevel);
}
// 追加静态缓冲区
this.appendBuffer(line.replace("\"", "\\\""));
// source.append("\t\tprintln(\"" + line.replace("\"", "\\\"") + "\");\r\n");
}
}
}
}
}
this.persistBuffer(source, false);
String simpleClassName = genTemplateClassName();
final String javaCode = getJavaCode(simpleClassName, importPackages, source);
this.templateJavaSource = javaCode.getBytes();
try {
templateClass = (TemplateClass) JDKCompiler.compileJavaSource(new JavaSourceObject(PACKAGE_NAME, simpleClassName, javaCode)).newInstance();
} catch (Throwable e) {
throw new ParserException(" parse exception :" + e.getMessage(), e);
}
}
private void appendIndent(StringBuilder source, int scopeLevel) {
while (scopeLevel-- > 0) {
source.append("\t");
}
}
private String genTemplateClassName() {
return String.format("StringTemplate$_%d", ATOMIC_LONG.getAndIncrement());
}
private String getJavaCode(String className, StringBuilder importPackages, StringBuilder source) {
StringBuilder javaCodeBuffer = new StringBuilder();
javaCodeBuffer.append(importPackages);
javaCodeBuffer.append("public class ").append(className).append(" extends TemplateClass {\r\n");
javaCodeBuffer.append("\r\n");
javaCodeBuffer.append("\tprotected void renderTemplate(final Map context) {\r\n").append(source).append("\r\n").append("\t}\r\n");
javaCodeBuffer.append("}");
return javaCodeBuffer.toString();
}
private void appendDefineSource(StringBuilder source, String line, String trimLine) {
this.persistBuffer(source);
if (trimLine.startsWith(DEFINE_PREFIX)) {
source.append("\t\t").append(trimLine.substring(DEFINE_PREFIX.length()));
} else {
source.append("\t\t").append(trimLine);
}
if (!trimLine.endsWith(";")) {
source.append(";");
}
source.append("\r\n");
}
/**
* 将line追加到缓冲区
*/
private void appendBuffer(String line) {
// println函数会自动追加换行, 临时静态字符串追加行文本（占一行）的最后一行不需要换行标识
if (staticTempBuffer.length() > 0) {
staticTempBuffer.append("\\r\\n");
}
staticTempBuffer.append(line);
}
/**
* 解析上下文，模板核心代码
*/
private void appendPlaceHolderLine(StringBuilder source, String line, String contextName, int scopeLevel) {
// 暂时只支持解析表达式，可拓展支持函数调用，后续支持
String reg = "[$][{]([ ]*[0-9a-zA-Z_.$]+[ ]*)[}]";
Pattern pattern = RegexUtils.getPattern(reg);
Matcher matcher = pattern.matcher(line);
int beginIndex = 0;
StringBuilder buffer = staticTempBuffer;
boolean hasNewlineFlag = false;
while (matcher.find()) {
// 判断group开始是否为转义标识符\\,如果是就原group跳过
int newBeginIndex = matcher.start(0);
if (newBeginIndex > 1 && line.charAt(newBeginIndex - 1) == '\\') {
if (!hasNewlineFlag) {
if (buffer.length() > 0) {
buffer.append("\\r\\n");
hasNewlineFlag = true;
}
}
buffer.append(line, beginIndex, newBeginIndex - 2);
buffer.append(matcher.group(0));
} else {
String key = matcher.group(1).trim();
buffer.append(line, beginIndex, newBeginIndex);
// 这里需要动态append值,先持久化
persistBuffer(source, false);
appendIndent(source, scopeLevel);
// 占位符实际替换代码
source.append("\t\tprint(getContextValue(" + contextName + ", \"" + key + "\", \"\"));\r\n");
appendIndent(source, scopeLevel);
}
beginIndex = matcher.end(0);
}
if (beginIndex < line.length()) {
// appendIndent(source, scopeLevel);
buffer.append(line, beginIndex, line.length());
} else {
nextNewLine = true;
}
}
/**
* 缓冲区持久化到source
*/
private void persistBuffer(StringBuilder source) {
persistBuffer(source, true);
}
/**
* 缓冲区持久化到source
*/
private void persistBuffer(StringBuilder source, int level) {
this.appendIndent(source, level);
persistBuffer(source, true);
}
/**
* 缓冲区持久化到source
*/
private void persistBuffer(StringBuilder source, boolean newLine) {
if (staticTempBuffer.length() > 0) {
if (newLine) {
// 临时静态字符串持久化到source
source.append("\t\tprintln(\"").append(staticTempBuffer).append("\");\r\n");
} else {
source.append("\t\tprint(\"").append(staticTempBuffer).append("\");\r\n");
}
// 重置
staticTempBuffer.setLength(0);
}
}
private boolean appendForLoopSource(StringBuilder source, String line, String trimLine) {
Matcher matcher = FOR_LOOP_PATTERN.matcher(trimLine);
boolean matched = false;
if (matcher.find()) {
matched = true;
String itemKey = matcher.group(1);
String indexKey = matcher.group(3);
String itemsKey = matcher.group(4);
source.append("\t\titerable = getContextIterable(context, \"" + itemsKey + "\");\r\n");
source.append("\t\tlocalContext = new HashMap(context);\r\n");
if (indexKey != null) {
source.append("\t\tindex = 0;\r\n");
}
source.append("\t\tfor (Object " + itemKey + " : iterable) {\r\n");
source.append("\t\t\tlocalContext.put(\"" + itemKey + "\", " + itemKey + ");\r\n");
if (indexKey != null) {
source.append("\t\t\tlocalContext.put(\"" + indexKey + "\", index++);\r\n");
}
} else {
// 理论上代码不可达，暂不处理
}
return matched;
}
private boolean appendIfClauseSource(StringBuilder source, String line, String trimLine) {
Matcher matcher = IF_PATTERN.matcher(trimLine);
boolean matched = false;
if (matcher.find()) {
matched = true;
String condition = matcher.group(1);
source.append("\t\tif(").append(condition).append("){\r\n");
} else {
// 理论上代码不可达，暂不处理
}
return matched;
}
private boolean appendElseIfClauseSource(StringBuilder source, String line, String trimLine) {
Matcher matcher = ELSE_IF_PATTERN.matcher(trimLine);
boolean matched = false;
if (matcher.find()) {
matched = true;
String condition = matcher.group(1);
source.append("\t\t} else if(").append(condition).append("){\r\n\t");
} else {
// 理论上代码不可达，暂不处理
}
return matched;
}
private void appendElseClauseSource(StringBuilder source, String line, String trimLine) {
source.append("\t\t} else {\r\n\t");
}
private Map context = new HashMap();
public void binding(String key, Object value) {
context.put(key, value);
}
public void binding(Map data) {
context.putAll(data);
}
public void clearBinging() {
context.clear();
}
public void clearBinging(String key) {
context.remove(key);
}
/***
* 生成模板串
*
* @return
*/
public synchronized String render() {
return render(context);
}
/**
* 以指定上下文渲染数据模板
*
* @param context
* @return
*/
public synchronized String render(Map context) {
return templateClass.render(context);
}
/***
* 返回实例id
*
* @return
*/
public final String getId() {
return templateId;
}
/**
* 获取模板源代码
*/
byte[] getTemplateJavaSource() {
return templateJavaSource;
}
}
