org.apache.juneau.svl.VarResolverSession Maven / Gradle / Ivy
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package org.apache.juneau.svl;
import static org.apache.juneau.internal.StringUtils.*;
import java.io.*;
import java.lang.reflect.*;
import java.util.*;
import org.apache.juneau.*;
/**
* A var resolver session that combines a {@link VarResolver} with one or more session objects.
*
*
* Instances of this class are considered light-weight and fast to construct, use, and discard.
*
*
* This class contains the workhorse code for var resolution.
*
*
* Instances of this class are created through the {@link VarResolver#createSession()} and
* {@link VarResolver#createSession(Map)} methods.
*
*
* Instances of this class are NOT guaranteed to be thread safe.
*
* @see org.apache.juneau.svl
*/
public class VarResolverSession {
private final VarResolverContext context;
private final Map sessionObjects;
/**
* Constructor.
*
* @param context
* The {@link VarResolver} context object that contains the {@link Var Vars} and context objects associated with
* that resolver.
* @param sessionObjects The session objects.
*
*/
public VarResolverSession(VarResolverContext context, Map sessionObjects) {
this.context = context;
this.sessionObjects = sessionObjects != null ? sessionObjects : new HashMap();
}
/**
* Adds a session object to this session.
*
* @param name The name of the session object.
* @param o The session object.
* @return This method (for method chaining).
*/
public VarResolverSession sessionObject(String name, Object o) {
sessionObjects.put(name, o);
return this;
}
/**
* Resolve all variables in the specified string.
*
* @param s
* The string to resolve variables in.
* @return
* The new string with all variables resolved, or the same string if no variables were found.
*
Returns null if the input was null .
*/
public String resolve(String s) {
if (s == null || s.isEmpty())
return s;
if (s.indexOf('$') == -1 && s.indexOf('\\') == -1)
return s;
// Special case where value consists of a single variable with no embedded variables (e.g. "$X{...}").
// This is a common case, so we want an optimized solution that doesn't involve string builders.
if (isSimpleVar(s)) {
String var = s.substring(1, s.indexOf('{'));
String val = s.substring(s.indexOf('{')+1, s.length()-1);
Var v = getVar(var);
if (v != null) {
try {
if (v.streamed) {
StringWriter sw = new StringWriter();
v.resolveTo(this, sw, val);
return sw.toString();
}
s = v.doResolve(this, val);
if (s == null)
s = "";
return resolve(s);
} catch (Exception e) {
return '{' + e.getLocalizedMessage() + '}';
}
}
return s;
}
try {
return resolveTo(s, new StringWriter()).toString();
} catch (IOException e) {
throw new RuntimeException(e); // Never happens.
}
}
/**
* Convenience method for resolving variables in arbitrary objects.
*
*
* Supports resolving variables in the following object types:
*
* - {@link CharSequence}
*
- Arrays containing values of type {@link CharSequence}.
*
- Collections containing values of type {@link CharSequence}.
*
Collection class must have a no-arg constructor.
* - Maps containing values of type {@link CharSequence}.
*
Map class must have a no-arg constructor.
*
*
* @param o The object.
* @return The same object if no resolution was needed, otherwise a new object or data structure if resolution was
* needed.
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public T resolve(T o) {
if (o == null)
return null;
if (o instanceof CharSequence)
return (T)resolve(o.toString());
if (o.getClass().isArray()) {
if (! containsVars(o))
return o;
Object o2 = Array.newInstance(o.getClass().getComponentType(), Array.getLength(o));
for (int i = 0; i < Array.getLength(o); i++)
Array.set(o2, i, resolve(Array.get(o, i)));
return (T)o2;
}
if (o instanceof Collection) {
try {
Collection c = (Collection)o;
if (! containsVars(c))
return o;
Collection c2 = c.getClass().newInstance();
for (Object o2 : c)
c2.add(resolve(o2));
return (T)c2;
} catch (Exception e) {
return o;
}
}
if (o instanceof Map) {
try {
Map m = (Map)o;
if (! containsVars(m))
return o;
Map m2 = m.getClass().newInstance();
for (Map.Entry e : (Set)m.entrySet())
m2.put(e.getKey(), resolve(e.getValue()));
return (T)m2;
} catch (Exception e) {
return o;
}
}
return o;
}
private static boolean containsVars(Object array) {
for (int i = 0; i < Array.getLength(array); i++) {
Object o = Array.get(array, i);
if (o instanceof CharSequence && o.toString().contains("$"))
return true;
}
return false;
}
@SuppressWarnings("rawtypes")
private static boolean containsVars(Collection c) {
for (Object o : c)
if (o instanceof CharSequence && o.toString().contains("$"))
return true;
return false;
}
@SuppressWarnings("rawtypes")
private static boolean containsVars(Map m) {
for (Object o : m.values())
if (o instanceof CharSequence && o.toString().contains("$"))
return true;
return false;
}
/*
* Checks to see if string is of the simple form "$X{...}" with no embedded variables.
* This is a common case, and we can avoid using StringWriters.
*/
private static boolean isSimpleVar(String s) {
int S1 = 1; // Not in variable, looking for $
int S2 = 2; // Found $, Looking for {
int S3 = 3; // Found {, Looking for }
int S4 = 4; // Found }
int length = s.length();
int state = S1;
for (int i = 0; i < length; i++) {
char c = s.charAt(i);
if (state == S1) {
if (c == '$') {
state = S2;
} else {
return false;
}
} else if (state == S2) {
if (c == '{') {
state = S3;
} else if (c < 'A' || c > 'z' || (c > 'Z' && c < 'a')) { // False trigger "$X "
return false;
}
} else if (state == S3) {
if (c == '}')
state = S4;
else if (c == '{' || c == '$')
return false;
} else if (state == S4) {
return false;
}
}
return state == S4;
}
/**
* Resolves variables in the specified string and sends the output to the specified writer.
*
*
* More efficient than first parsing to a string and then serializing to the writer since this method doesn't need
* to construct a large string.
*
* @param s The string to resolve variables in.
* @param out The writer to write to.
* @return The same writer.
* @throws IOException
*/
public Writer resolveTo(String s, Writer out) throws IOException {
int S1 = 1; // Not in variable, looking for $
int S2 = 2; // Found $, Looking for {
int S3 = 3; // Found {, Looking for }
int state = S1;
boolean isInEscape = false;
boolean hasInternalVar = false;
boolean hasInnerEscapes = false;
String varType = null;
String varVal = null;
int x = 0, x2 = 0;
int depth = 0;
int length = s.length();
for (int i = 0; i < length; i++) {
char c = s.charAt(i);
if (state == S1) {
if (isInEscape) {
if (c == '\\' || c == '$') {
out.append(c);
} else {
out.append('\\').append(c);
}
isInEscape = false;
} else if (c == '\\') {
isInEscape = true;
} else if (c == '$') {
x = i;
x2 = i;
state = S2;
} else {
out.append(c);
}
} else if (state == S2) {
if (isInEscape) {
isInEscape = false;
} else if (c == '\\') {
hasInnerEscapes = true;
isInEscape = true;
} else if (c == '{') {
varType = s.substring(x+1, i);
x = i;
state = S3;
} else if (c < 'A' || c > 'z' || (c > 'Z' && c < 'a')) { // False trigger "$X "
if (hasInnerEscapes)
out.append(unEscapeChars(s.substring(x, i+1), new char[]{'\\','{'}));
else
out.append(s, x, i+1);
x = i + 1;
state = S1;
hasInnerEscapes = false;
}
} else if (state == S3) {
if (isInEscape) {
isInEscape = false;
} else if (c == '\\') {
isInEscape = true;
hasInnerEscapes = true;
} else if (c == '{') {
depth++;
hasInternalVar = true;
} else if (c == '}') {
if (depth > 0) {
depth--;
} else {
varVal = s.substring(x+1, i);
varVal = (hasInternalVar ? resolve(varVal) : varVal);
Var r = getVar(varType);
if (r == null) {
if (hasInnerEscapes)
out.append(unEscapeChars(s.substring(x2, i+1), new char[]{'\\','$','{','}'}));
else
out.append(s, x2, i+1);
x = i+1;
} else {
try {
if (r.streamed)
r.resolveTo(this, out, varVal);
else {
String replacement = r.doResolve(this, varVal);
if (replacement == null)
replacement = "";
// If the replacement also contains variables, replace them now.
if (replacement.indexOf('$') != -1)
replacement = resolve(replacement);
out.append(replacement);
}
} catch (Exception e) {
out.append('{').append(e.getLocalizedMessage()).append('}');
}
x = i+1;
}
state = 1;
hasInnerEscapes = false;
}
}
}
}
if (isInEscape)
out.append('\\');
else if (state == S2)
out.append('$').append(unEscapeChars(s.substring(x+1), new char[]{'{', '\\'}));
else if (state == S3)
out.append('$').append(varType).append('{').append(unEscapeChars(s.substring(x+1), new char[]{'\\','$','{','}'}));
return out;
}
/**
* Returns the session object with the specified name.
*
*
* Casts it to the specified class type for you.
*
* @param c The class type to cast to.
* @param name The name of the session object.
* @return The session object. Never null .
* @throws RuntimeException If session object with specified name does not exist.
*/
@SuppressWarnings("unchecked")
public T getSessionObject(Class c, String name) {
T t = null;
try {
t = (T)sessionObjects.get(name);
if (t == null) {
sessionObjects.put(name, this.context.getContextObject(name));
t = (T)sessionObjects.get(name);
}
} catch (Exception e) {
throw new FormattedRuntimeException(e,
"Session object ''{0}'' or context object ''SvlContext.{0}'' could not be converted to type ''{1}''.", name, c);
}
if (t == null)
throw new FormattedRuntimeException(
"Session object ''{0}'' or context object ''SvlContext.{0}'' not found.", name);
return t;
}
/**
* Returns the {@link Var} with the specified name.
*
* @param name The var name (e.g. "S" ).
* @return The {@link Var} instance, or null if no Var is associated with the specified name.
*/
protected Var getVar(String name) {
return this.context.getVarMap().get(name);
}
}