2021SC@SDUSC
core.DirectiveCallPlace及其子类
总览图：
1.接口DirectiveCallPlace
代码：
public interface DirectiveCallPlace {
Template getTemplate();
int getBeginColumn();
int getBeginLine();
int getEndLine();
Object getOrCreateCustomData(Object providerIdentity, ObjectFactory objectFactory)
throws CallPlaceCustomDataInitializationException;
boolean isNestedOutputCacheable();
}
作用：提供有关调用指令的位置的信息，还允许将自定义数据对象附加到该位置。模板中的每个指令调用都有自己的 DirectiveCallPlace对象(即使它们使用相同的参数调用相同的指令)。DirectiveCallPlace对象的生命周期绑定到包含指令调用的Template对象。因此，DirectiveCallPlace对象和你放入其中的自定义数据会与Template一起缓存。
2.UnifiedCall类
代码：
final class UnifiedCall extends TemplateElement implements DirectiveCallPlace {
private Expression nameExp;
private Map<String, ? extends Expression> namedArgs;
private List<? extends Expression> positionalArgs;
private List<String> bodyParameterNames;
boolean legacySyntax;
private transient volatile SoftReference/*List<Map.Entry<String,Expression>>*/ sortedNamedArgsCache;
private CustomDataHolder customDataHolder;
UnifiedCall(Expression nameExp,
Map<String, ? extends Expression> namedArgs,
TemplateElements children,
List<String> bodyParameterNames) {
this.nameExp = nameExp;
this.namedArgs = namedArgs;
setChildren(children);
this.bodyParameterNames = bodyParameterNames;
}
UnifiedCall(Expression nameExp,
List<? extends Expression> positionalArgs,
TemplateElements children,
List<String> bodyParameterNames) {
this.nameExp = nameExp;
this.positionalArgs = positionalArgs;
setChildren(children);
this.bodyParameterNames = bodyParameterNames;
}
@Override
TemplateElement[] accept(Environment env) throws TemplateException, IOException {
TemplateModel tm = nameExp.eval(env);
if (tm == Macro.DO_NOTHING_MACRO) return null; // shortcut here.
if (tm instanceof Macro) {
Macro macro = (Macro) tm;
if (macro.isFunction() && !legacySyntax) {
throw new _MiscTemplateException(env,
"Routine ", new _DelayedJQuote(macro.getName()), " is a function, not a directive. "
+ "Functions can only be called from expressions, like in ${f()}, ${x + f()} or ",
"<@someDirective someParam=f() />", ".");
}
env.invokeMacro(macro, namedArgs, positionalArgs, bodyParameterNames, this);
} else {
boolean isDirectiveModel = tm instanceof TemplateDirectiveModel;
if (isDirectiveModel || tm instanceof TemplateTransformModel) {
Map args;
if (namedArgs != null && !namedArgs.isEmpty()) {
args = new HashMap();
for (Iterator it = namedArgs.entrySet().iterator(); it.hasNext(); ) {
Map.Entry entry = (Map.Entry) it.next();
String key = (String) entry.getKey();
Expression valueExp = (Expression) entry.getValue();
TemplateModel value = valueExp.eval(env);
args.put(key, value);
}
} else {
args = EmptyMap.instance;
}
if (isDirectiveModel) {
env.visit(getChildBuffer(), (TemplateDirectiveModel) tm, args, bodyParameterNames);
} else {
env.visitAndTransform(getChildBuffer(), (TemplateTransformModel) tm, args);
}
} else if (tm == null) {
throw InvalidReferenceException.getInstance(nameExp, env);
} else {
throw new NonUserDefinedDirectiveLikeException(nameExp, tm, env);
}
}
return null;
}
@Override
protected String dump(boolean canonical) {
StringBuilder sb = new StringBuilder();
if (canonical) sb.append('<');
sb.append('@');
_MessageUtil.appendExpressionAsUntearable(sb, nameExp);
boolean nameIsInParen = sb.charAt(sb.length() - 1) == ')';
if (positionalArgs != null) {
for (int i = 0; i < positionalArgs.size(); i++) {
Expression argExp = positionalArgs.get(i);
if (i != 0) {
sb.append(',');
}
sb.append(' ');
sb.append(argExp.getCanonicalForm());
}
} else {
List entries = getSortedNamedArgs();
for (int i = 0; i < entries.size(); i++) {
Map.Entry entry = (Map.Entry) entries.get(i);
Expression argExp = (Expression) entry.getValue();
sb.append(' ');
sb.append(_CoreStringUtils.toFTLTopLevelIdentifierReference((String) entry.getKey()));
sb.append('=');
_MessageUtil.appendExpressionAsUntearable(sb, argExp);
}
}
if (bodyParameterNames != null && !bodyParameterNames.isEmpty()) {
sb.append("; ");
for (int i = 0; i < bodyParameterNames.size(); i++) {
if (i != 0) {
sb.append(", ");
}
sb.append(_CoreStringUtils.toFTLTopLevelIdentifierReference(bodyParameterNames.get(i)));
}
}
if (canonical) {
if (getChildCount() == 0) {
sb.append("/>");
} else {
sb.append('>');
sb.append(getChildrenCanonicalForm());
sb.append("</@");
if (!nameIsInParen
&& (nameExp instanceof Identifier
|| (nameExp instanceof Dot && ((Dot) nameExp).onlyHasIdentifiers()))) {
sb.append(nameExp.getCanonicalForm());
}
sb.append('>');
}
}
return sb.toString();
}
@Override
String getNodeTypeSymbol() {
return "@";
}
@Override
int getParameterCount() {
return 1/*nameExp*/
+ (positionalArgs != null ? positionalArgs.size() : 0)
+ (namedArgs != null ? namedArgs.size() * 2 : 0)
+ (bodyParameterNames != null ? bodyParameterNames.size() : 0);
}
@Override
Object getParameterValue(int idx) {
if (idx == 0) {
return nameExp;
} else {
int base = 1;
final int positionalArgsSize = positionalArgs != null ? positionalArgs.size() : 0;
if (idx - base < positionalArgsSize) {
return positionalArgs.get(idx - base);
} else {
base += positionalArgsSize;
final int namedArgsSize = namedArgs != null ? namedArgs.size() : 0;
if (idx - base < namedArgsSize * 2) {
Map.Entry namedArg = (Map.Entry) getSortedNamedArgs().get((idx - base) / 2);
return (idx - base) % 2 == 0 ? namedArg.getKey() : namedArg.getValue();
} else {
base += namedArgsSize * 2;
final int bodyParameterNamesSize = bodyParameterNames != null ? bodyParameterNames.size() : 0;
if (idx - base < bodyParameterNamesSize) {
return bodyParameterNames.get(idx - base);
} else {
throw new IndexOutOfBoundsException();
}
}
}
}
}
@Override
ParameterRole getParameterRole(int idx) {
if (idx == 0) {
return ParameterRole.CALLEE;
} else {
int base = 1;
final int positionalArgsSize = positionalArgs != null ? positionalArgs.size() : 0;
if (idx - base < positionalArgsSize) {
return ParameterRole.ARGUMENT_VALUE;
} else {
base += positionalArgsSize;
final int namedArgsSize = namedArgs != null ? namedArgs.size() : 0;
if (idx - base < namedArgsSize * 2) {
return (idx - base) % 2 == 0 ? ParameterRole.ARGUMENT_NAME : ParameterRole.ARGUMENT_VALUE;
} else {
base += namedArgsSize * 2;
final int bodyParameterNamesSize = bodyParameterNames != null ? bodyParameterNames.size() : 0;
if (idx - base < bodyParameterNamesSize) {
return ParameterRole.TARGET_LOOP_VARIABLE;
} else {
throw new IndexOutOfBoundsException();
}
}
}
}
}
private List/*<Map.Entry<String, Expression>>*/ getSortedNamedArgs() {
Reference ref = sortedNamedArgsCache;
if (ref != null) {
List res = (List) ref.get();
if (res != null) return res;
}
List res = MiscUtil.sortMapOfExpressions(namedArgs);
sortedNamedArgsCache = new SoftReference(res);
return res;
}
@Override
@SuppressFBWarnings(value={ "IS2_INCONSISTENT_SYNC", "DC_DOUBLECHECK" }, justification="Performance tricks")
public Object getOrCreateCustomData(Object providerIdentity, ObjectFactory objectFactory)
throws CallPlaceCustomDataInitializationException {
// We are using double-checked locking, utilizing Java memory model "final" trick.
// Note that this.customDataHolder is NOT volatile.
CustomDataHolder customDataHolder = this.customDataHolder; // Findbugs false alarm
if (customDataHolder == null) { // Findbugs false alarm
synchronized (this) {
customDataHolder = this.customDataHolder;
if (customDataHolder == null || customDataHolder.providerIdentity != providerIdentity) {
customDataHolder = createNewCustomData(providerIdentity, objectFactory);
this.customDataHolder = customDataHolder;
}
}
}
if (customDataHolder.providerIdentity != providerIdentity) {
synchronized (this) {
customDataHolder = this.customDataHolder;
if (customDataHolder == null || customDataHolder.providerIdentity != providerIdentity) {
customDataHolder = createNewCustomData(providerIdentity, objectFactory);
this.customDataHolder = customDataHolder;
}
}
}
return customDataHolder.customData;
}
private CustomDataHolder createNewCustomData(Object provierIdentity, ObjectFactory objectFactory)
throws CallPlaceCustomDataInitializationException {
CustomDataHolder customDataHolder;
Object customData;
try {
customData = objectFactory.createObject();
} catch (Exception e) {
throw new CallPlaceCustomDataInitializationException(
"Failed to initialize custom data for provider identity "
+ StringUtil.tryToString(provierIdentity) + " via factory "
+ StringUtil.tryToString(objectFactory), e);
}
if (customData == null) {
throw new NullPointerException("ObjectFactory.createObject() has returned null");
}
customDataHolder = new CustomDataHolder(provierIdentity, customData);
return customDataHolder;
}
@Override
public boolean isNestedOutputCacheable() {
return isChildrenOutputCacheable();
}
private static class CustomDataHolder {
private final Object providerIdentity;
private final Object customData;
public CustomDataHolder(Object providerIdentity, Object customData) {
this.providerIdentity = providerIdentity;
this.customData = customData;
}
}
@Override
boolean isNestedBlockRepeater() {
return true;
}
@Override
boolean isShownInStackTrace() {
return true;
}
}
作用：用于调用宏/指令/转换的元素。
注：Freemarker代码来自FreeMarker 中文官方参考手册
新手写的代码分析，文章若有错误还请指出