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com.github.mustachejava.reflect.ReflectionObjectHandler Maven / Gradle / Ivy
package com.github.mustachejava.reflect;
import static java.util.Collections.*;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.github.mustachejava.Binding;
import com.github.mustachejava.Code;
import com.github.mustachejava.ObjectHandler;
import com.github.mustachejava.TemplateContext;
import com.github.mustachejava.reflect.guards.ClassGuard;
import com.github.mustachejava.reflect.guards.DepthGuard;
import com.github.mustachejava.reflect.guards.DotGuard;
import com.github.mustachejava.reflect.guards.MapGuard;
import com.github.mustachejava.reflect.guards.NullGuard;
import com.github.mustachejava.reflect.guards.WrappedGuard;
import com.github.mustachejava.util.GuardException;
import com.github.mustachejava.util.Wrapper;
/**
* Lookup objects using reflection and execute them the same way.
*
* User: sam
* Date: 7/24/11
* Time: 3:02 PM
*/
public class ReflectionObjectHandler extends BaseObjectHandler {
protected static final Method MAP_METHOD;
public static Object unwrap(ObjectHandler oh, int scopeIndex, Wrapper[] wrappers, List scopes) throws GuardException {
Object scope = oh.coerce(scopes.get(scopeIndex));
// The value may be buried by . notation
if (wrappers != null) {
for (Wrapper wrapper : wrappers) {
scope = oh.coerce(wrapper.call(ObjectHandler.makeList(scope)));
}
}
return scope;
}
static {
try {
MAP_METHOD = Map.class.getMethod("get", Object.class);
} catch (NoSuchMethodException e) {
throw new AssertionError(e);
}
}
@SuppressWarnings("unchecked")
@Override
public Wrapper find(String name, final List scopes) {
Wrapper wrapper = null;
final int length = scopes.size();
List guards = new ArrayList<>(length);
// Simple guard to break if the number of scopes at this call site have changed
guards.add(createDepthGuard(length));
NEXT:
for (int i = length - 1; i >= 0; i--) {
Object scope = scopes.get(i);
if (scope == null) continue;
// Make sure that the current scope is the same class
guards.add(createClassGuard(i, scope));
List wrappers = null;
int dotIndex;
String subname = name;
// Try and find a wrapper using the simple name
wrapper = findWrapper(i, null, guards, scope, subname);
if (wrapper != null) {
break;
}
// If there is dot notation, start evaluating it
while ((dotIndex = subname.indexOf('.')) != -1) {
final String lookup = subname.substring(0, dotIndex);
subname = subname.substring(dotIndex + 1);
// This is used for lookups but otherwise always succeeds
guards.add(createDotGuard(i, scope, lookup));
List wrapperGuard = new ArrayList<>(1);
wrapperGuard.add(createClassGuard(0, scope));
wrapper = findWrapper(0, null, wrapperGuard, scope, lookup);
if (wrappers == null) wrappers = new ArrayList<>();
if (wrapper != null) {
// We need to dig into a scope when dot notation shows up
wrappers.add(wrapper);
try {
// Pull out the next level
scope = coerce(wrapper.call(ObjectHandler.makeList(scope)));
} catch (GuardException e) {
throw new AssertionError(e);
}
} else {
// Failed to find a wrapper for the next dot
guards.add(createWrappedGuard(i, wrappers, wrapperGuard));
continue NEXT;
}
if (scope == null) {
// Found a wrapper, but the result of was null
guards.add(createWrappedGuard(i, wrappers, singletonList(createNullGuard())));
// Break here to allow the wrapper to be returned with the partial evaluation of the dot notation
break;
}
}
if (wrappers != null) {
guards.add(createWrappedGuard(i, wrappers, singletonList((Guard) createClassGuard(0, scope))));
}
Wrapper[] foundWrappers = wrappers == null ? null : wrappers.toArray(new Wrapper[wrappers.size()]);
wrapper = findWrapper(i, foundWrappers, guards, scope, subname);
if (wrapper == null) {
// If we have found any wrappers we need to keep them rather than return a missing wrapper
// otherwise it will continue you on to other scopes and break context precedence
if (wrappers != null) {
wrapper = createMissingWrapper(subname, guards);
break;
}
} else {
break;
}
}
return wrapper == null ? createMissingWrapper(name, guards) : wrapper;
}
/**
* Find a wrapper given the current context. If not found, return null.
*
* @param scopeIndex the index into the scope array
* @param wrappers the current set of wrappers to get here
* @param guards the list of guards used to find this
* @param scope the current scope
* @param name the name in the scope
* @return null if not found, otherwise a wrapper for this scope and name
*/
protected Wrapper findWrapper(final int scopeIndex, Wrapper[] wrappers, List guards, Object scope, final String name) {
scope = coerce(scope);
if (scope == null) return null;
// If the scope is a map, then we use the get() method
// to see if it contains a value named name.
if (scope instanceof Map) {
Map map = (Map) scope;
if (map.containsKey(name)) {
guards.add(createMapGuard(scopeIndex, wrappers, name, true));
return createWrapper(scopeIndex, wrappers, guards, MAP_METHOD, new Object[]{name});
} else {
guards.add(createMapGuard(scopeIndex, wrappers, name, false));
if (!areMethodsAccessible(map)) {
return null;
}
}
}
AccessibleObject member = findMember(scope.getClass(), name);
return member == null ? null : createWrapper(scopeIndex, wrappers, guards, member, new Object[0]);
}
// Factories
protected MissingWrapper createMissingWrapper(String name, List guards) {
return new MissingWrapper(name, guards.toArray(new Guard[guards.size()]));
}
protected DotGuard createDotGuard(int i, Object scope, String lookup) {
return new DotGuard(lookup, i, scope);
}
protected WrappedGuard createWrappedGuard(int i, List wrappers, List wrapperGuard) {
return new WrappedGuard(this, i, wrappers, wrapperGuard);
}
protected NullGuard createNullGuard() {
return new NullGuard();
}
protected DepthGuard createDepthGuard(int length) {
return new DepthGuard(length);
}
protected ClassGuard createClassGuard(int i, Object scope) {
return new ClassGuard(i, scope);
}
protected MapGuard createMapGuard(int scopeIndex, Wrapper[] wrappers, String name, boolean contains) {
return new MapGuard(this, scopeIndex, name, contains, wrappers);
}
@SuppressWarnings("unchecked")
protected Wrapper createWrapper(int scopeIndex, Wrapper[] wrappers, List guard, AccessibleObject member, Object[] arguments) {
return new ReflectionWrapper(scopeIndex, wrappers, guard.toArray(new Guard[guard.size()]), member, arguments, this);
}
@Override
public Binding createBinding(String name, TemplateContext tc, Code code) {
return new GuardedBinding(this, name, tc, code);
}
protected boolean areMethodsAccessible(Map map) {
return false;
}
}
