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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package org.graalvm.polyglot;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Predicate;
import java.util.logging.Handler;
import java.util.logging.Level;
import org.graalvm.polyglot.impl.AbstractPolyglotImpl.AbstractContextImpl;
import org.graalvm.polyglot.proxy.Proxy;
import org.graalvm.polyglot.io.FileSystem;
/**
* A polyglot context for Graal guest languages that allows to {@link #eval(Source) evaluate} code.
* A polyglot context represents the global runtime state of all {@link Engine#getLanguages()
* installed} and {@link #newBuilder(String...) permitted} languages. Permitted languages are
* {@link #initialize(String) initialized} lazily, when they are used for the first time. For many
* operations of the context, a language identifier needs to be specified. A language
* identifier is unique for each language.
*
* Evaluation
*
* A context allows to evaluate Guest language source code using {@link #eval(Source)}. This is
* possible by evaluating {@link Source} objects or given a language identifier and code
* {@link String}. The {@link #eval(Source) evaluation} returns either the result value or throws a
* {@link PolyglotException} if a guest language error occurs.
*
* Example for evaluation of a fragment of JavaScript code with a new context:
*
*
* Context context = Context.create();
* Value result = context.eval("js", "42");
* assert result.asInt() == 42;
* context.close();
*
*
* In this example:
*
* - We first first create a new context with all installed languages as permitted languages.
*
- Next, we evaluate the expression "42" with language "js", which is the language identifier
* for JavaScript. Since this is the first time we access JavaScript, it automatically gets
* {@link #initialize(String) initialized} first.
*
- Then, we assert the result value by converting the result value as primitive
int
* .
* - Finally, if the context is no longer needed, it is necessary to close it to ensure that all
* resources are freed. Contexts are also {@link AutoCloseable} for use with the Java
* {@code try-with-resources} statement.
*
*
* Configuration
*
* Contexts may be created either with default configuration using the {@link #create(String...)
* create method} or with custom configuration using the {@link #newBuilder(String...) builder}.
* Both methods allow to specify a subset of the installed languages as permitted languages. If no
* language is specified then all installed languages are permitted. Using the builder method
* {@link Builder#in(InputStream) input}, {@link Builder#err(OutputStream) error} and
* {@link Builder#out(OutputStream) output} streams, {@link Builder#option(String, String) options},
* and {@link Builder#arguments(String, String[]) application arguments} may be configured.
*
* Options may be specified for {@link Engine#getLanguages() languages},
* {@link Engine#getInstruments() instruments}, the {@link Engine#getOptions() engine} and the
* {@link Engine#getOptions() compiler}. For {@link Language#getOptions() language options} the
* option key consists of the {@link Language#getId() language id} plus a dot followed by the option
* name (e.g. "js.Strict"). For most languages the option names start with an upper-case letter by
* convention. A list of available options may be received using {@link Language#getOptions()}.
* {@link Instrument#getOptions() Instrument options} are structured in the same way as language
* options but start with the {@link Instrument#getId() instrument id} instead.
*
* If system properties are {@link Engine.Builder#useSystemProperties(boolean) enabled}, which they
* are by default, then all polyglot options maybe specified with the prefix "polyglot." (e.g.
* "-Dpolyglot.js.Strict=true"). The system properties are read only once when the context or engine
* instance is created. After that changes to the system properties have no affect.
*
* Each Graal language performs an initialization step before it can be used to execute code, after
* which it remains initialized for the lifetime of the context. Initialization is by default lazy
* and automatic, but initialization can be forced {@link Context#initialize(String) manually} if
* needed.
*
* Example for custom configuration using the context builder:
*
*
* OutputStream myOut = new BufferedOutputStream()
* Context context = Context.newBuilder("js", "R")
* .out(myOut)
* .option("js.Strict", "true")
* .allowAllAccess(true)
* .build();
* context.eval("js", "42");
* context.eval("R", "42");
* context.close();
*
*
* In this example:
*
* - We first first create a new context with all installed languages as permitted languages.
*
- Next, we evaluate the expression "42" with language "js", which is the language identifier
* for JavaScript. Since this is the first time we access JavaScript, it first gets
* {@link #initialize(String) initialized} as well.
*
- Then, we assert the result value by converting the result value as primitive
int
* .
* - Finally, if the context is no longer needed, it is necessary to close it to ensure that all
* resources are freed. Contexts are also {@link AutoCloseable} for use with the Java
* {@code try-with-resources} statement.
*
*
* Bindings
*
* The symbols of the top-most scope of a language can be accessed using the
* {@link #getBindings(String) language bindings}. Each language provides its own bindings object
* for a context. The bindings object may be used to read, modify, insert and delete members in the
* top-most scope of the language. Certain languages may not allow write access to the bindings
* object. See {@link #getBindings(String)} for details.
*
* A context instance also provides access to the {@link #getPolyglotBindings() polyglot} bindings.
* The polyglot bindings are shared between languages and may be used to exchange values. See
* {@link #getPolyglotBindings()} for details.
*
* Examples using language bindings from JavaScript:
*
*
* Context context = Context.create("js");
* Value jsBindings = context.getBindings("js")
*
* jsBindings.putMember("foo", 42);
* assert context.eval("js", "foo").asInt() == 42;
*
* context.eval("js", "var bar = 42");
* assert jsBindings.getMember("bar").asInt() == 42;
*
* assert jsBindings.getMember("Math")
* .getMember("abs")
* .execute(-42)
* .asInt() == 42;
* context.close();
*
*
* In this example:
*
* - We create a new context with JavaScript as the only permitted language.
*
- Next, we load the JavaScript bindings object and assign it to a local variable
*
jsBindings.
* - Then, we insert a new member
foo into to the bindings object and verify that the
* object is accessible within the language by reading from a global symbol with the same name.
* - After that, we declare a new global variable in JavaScript and verify that it is accessible
* as member of the language bindings object.
*
- Next, we access we access a JavaScript builtin named
Math.abs symbol and execute
* it with -42. This result is asserted to be 42.
* - Finally, we close the context to free all allocated resources.
*
*
* Host Interoperability
*
* It is often necessary to interact with values of the host runtime within Graal guest languages.
* Such objects are referred to as host objects. Every Java value that is passed to a Graal
* language is interpreted according to the specification described in {@link #asValue(Object)}.
* Also see {@link Value#as(Class)} for further details.
*
*
* Example using a Java object from JavaScript:
*
*
* public class JavaRecord {
* public int x;
*
* public String name() {
* return "foo";
* }
* }
* Context context = Context.create();
*
* JavaRecord record = new JavaRecord();
* context.getBindings("js").putMember("javaRecord", record);
*
* context.eval("js", "record.x = 42");
* assert record.x == 42;
*
* context.eval("js", "record.name()").asString().equals("foo");
*
*
* Error Handling
*
* Guest languages code may fail when executing guest language code or when accessing guest language
* object. So almost all methods in the {@link Context} and {@link Value} API throw a
* {@link PolyglotException} in case an error occurs. See {@link PolyglotException} for further
* details on error handling.
*
* Isolation
*
* Each context is by default isolated from all other instances with respect to both language
* evaluation semantics and resource consumption. By default a new context instance has no access to
* host resources, like threads, files or loading new host classes. To allow access to such
* resources either the individual access right must be granted or
* {@link Builder#allowAllAccess(boolean) all access} must be set to true.
*
*
* Contexts can be {@linkplain Builder#engine(Engine) configured} to share certain system resources
* like ASTs, optimized code by specifying a single underlying engine; see {@link Engine} for more
* details about code sharing.
*
*
Proxies
*
* The {@link Proxy proxy interfaces} allow to mimic guest language objects, arrays, executables,
* primitives and native objects in Graal languages. Every Graal language will treat instances of
* proxies like an object of that particular language. Multiple proxy interfaces can be implemented
* at the same time. For example, it is useful to provide proxy values that are objects with members
* and arrays at the same time.
*
* Thread-Safety
*
* It is safe to use a context instance from a single thread. It is also safe to use it with
* multiple threads if they do not access the context at the same time. Whether a single context
* instance may be used from multiple threads at the same time depends on if all initialized
* languages support it. If only languages are initialized that support multi-threading then the
* context instance may be used from multiple threads at the same time. If a context is used from
* multiple threads and the language does not fit then an {@link IllegalStateException} is thrown by
* the accessing method.
*
* Meta-data from the context's underlying {@link #getEngine() engine} can be retrieved safely by
* any thread at any time.
*
* A context may be {@linkplain #close() closed} from any thread, but only if the context is not
* currently executing code. If a context is currently executing code, a different thread may kill
* the currently runnign execution and close the context using {@link #close(boolean)}.
*
*
Pre-Initialization
*
* The Context pre-initialization can be used to perform expensive builtin creation in the time of
* native compilation.
*
* The context pre-initialization is enabled by setting the system property
* {@code polyglot.engine.PreinitializeContexts} to a comma separated list of language ids which
* should be pre-initialized, for example: {@code -Dpolyglot.engine.PreinitializeContexts=js,python}
*
* See
* {@code com.oracle.truffle.api.TruffleLanguage.patchContext(java.lang.Object, com.oracle.truffle.api.TruffleLanguage.Env)}
* for details about pre-initialization for language implementers.
*
* @since 1.0
*/
public final class Context implements AutoCloseable {
final AbstractContextImpl impl;
Context(AbstractContextImpl impl) {
this.impl = impl;
}
/**
* Provides access to meta-data about the underlying Graal {@linkplain Engine engine}.
*
* @return the Graal {@link Engine} being used by this context
* @since 1.0
*/
public Engine getEngine() {
return impl.getEngineImpl(this);
}
/**
* Evaluates a source by using the {@linkplain Source#getLanguage() language} specified in the
* source. The result is accessible as {@link Value value} and never null. The
* first time a source is evaluated it will be parsed, consecutive invocations of eval with the
* same source will only execute the already parsed code.
*
* Basic Example:
*
*
* Context context = Context.create();
* Source source = Source.newBuilder("js", "42").name("mysource.js").build();
* Value result = context.eval(source);
* assert result.asInt() == 42;
* context.close();
*
*
* @param source a source object to evaluate
* @throws PolyglotException in case parsing or evaluation of the guest language code failed.
* @throws IllegalStateException if the context is already closed, the current thread is not
* allowed to access this context
* @throws IllegalArgumentException if the language of the given source is not installed or the
* {@link Source#getMimeType() MIME type} is not supported with the language.
* @return result of the evaluation. The returned instance is is never null, but
* the result might represent a {@link Value#isNull() null} value.
* @since 1.0
*/
public Value eval(Source source) {
return impl.eval(source.getLanguage(), source.impl);
}
/**
* Evaluates a guest language code literal, using a provided {@link Language#getId() language
* id}. The result is accessible as {@link Value value} and never null. The
* provided {@link CharSequence} must represent an immutable String.
*
* Basic Example:
*
*
* Context context = Context.create();
* Value result = context.eval("js", "42");
* assert result.asInt() == 42;
* context.close();
*
*
* @throws PolyglotException in case parsing or evaluation of the guest language code failed.
* @throws IllegalArgumentException if the language does not exist or is not accessible.
* @throws IllegalStateException if the context is already closed, the current thread is not
* allowed to access this context or if the given language is not installed.
* @return result of the evaluation. The returned instance is is never null, but
* the result might represent a {@link Value#isNull() null} value.
* @since 1.0
*/
public Value eval(String languageId, CharSequence source) {
return eval(Source.create(languageId, source));
}
/**
* Returns polyglot bindings that may be used to exchange symbols between the host and guest
* languages. All languages have unrestricted access to the polyglot bindings. The returned
* bindings object always has {@link Value#hasMembers() members} and its members are
* {@link Value#getMember(String) readable}, {@link Value#putMember(String, Object) writable}
* and {@link Value#removeMember(String) removable}.
*
* Guest languages may put and get members through language specific APIs. For example, in
* JavaScript symbols of the polyglot bindings can be accessed using
* Polyglot.import("name") and set using
* Polyglot.export("name", value). Please see the individual language reference on
* how to access these symbols.
*
* @throws IllegalStateException if context is already closed.
* @since 1.0
*/
public Value getPolyglotBindings() {
return impl.getPolyglotBindings();
}
/**
* Returns a value that represents the top-most bindings of a language. The top most bindings of
* the language returns a {@link Value#getMember(String) member} for symbol in the scope.
* Languages may allow modifications of members of the returned bindings object at the
* language's discretion. If the language was not yet {@link #initialize(String) initialized} it
* will be initialized when the bindings are requested.
*
* @throws IllegalArgumentException if the language does not exist or is not accessible.
* @throws IllegalStateException if the context is already closed.
* @throws PolyglotException in case the lazy initialization failed due to a guest language
* error.
* @since 1.0
*/
public Value getBindings(String languageId) {
return impl.getBindings(languageId);
}
/**
* Forces the initialization of a language. It is not necessary to explicitly initialize a
* language, it will be initialized the first time it is used.
*
* @param languageId the identifier of the language to initialize.
* @return true if the language was initialized. Returns false if it
* was already initialized.
* @throws PolyglotException in case the initialization failed due to a guest language error.
* @throws IllegalArgumentException if the language does not exist or is not accessible.
* @throws IllegalStateException if the context is already closed.
* @since 1.0
*/
public boolean initialize(String languageId) {
return impl.initializeLanguage(languageId);
}
/**
* Converts a host value to a polyglot {@link Value value} representation. This conversion is
* applied implicitly whenever {@link Value#execute(Object...) execution} or
* {@link Value#newInstance(Object...) instantiation} arguments are provided,
* {@link Value#putMember(String, Object) members} and
* {@link Value#setArrayElement(long, Object) array elements} are set or when a value is
* returned by a {@link Proxy polyglot proxy}. It is not required nor efficient to explicitly
* convert to polyglot values before performing these operations. This method is useful to
* convert a {@link Value#as(Class) mapped} host value back to a polyglot value while preserving
* the identity.
*
* When a host value is converted to a polyglot value the following rules apply:
*
* - If the
hostValue is null then it will be interpreted as
* polyglot {@link Value#isNull() null}.
* - If the
hostValue is already a {@link Value polyglot value} then it will be
* cast to {@link Value}.
* - If the
hostValue is an instance of {@link Byte}, {@link Short},
* {@link Integer}, {@link Long}, {@link Float} or {@link Double} then it will be interpreted as
* polyglot {@link Value#isNumber() number}. Other subclasses of {@link Number} will be
* interpreted as {@link Value#isHostObject() host object} (see later).
* - If the
hostValue is an instance of {@link Character} or {@link String} then
* it will be interpreted as polyglot {@link Value#isString() string}.
* - If the
hostValue is an instance of {@link Boolean} then it will be
* interpreted as polyglot {@link Value#isBoolean() boolean}.
* - If the
hostValue is a {@link Proxy polyglot proxy} then it will be
* interpreted according to the behavior specified by the proxy. See the javadoc of the proxy
* subclass for further details.
* - If the
hostValue is a non-primitive {@link Value#as(Class) mapped Java
* value} then the original value will be restored. For example if a guest language object was
* mapped to {@link Map} then the original object identity will be preserved when converting
* back to a polyglot value.
* - Any other
hostValue will be interpreted as {@link Value#isHostObject() host
* object}. Host objects expose all their public java fields and methods as
* {@link Value#getMember(String) members}. In addition, Java arrays and subtypes of
* {@link List} will be interpreted as value with {@link Value#hasArrayElements() array
* elements} and single method interfaces annotated with {@link FunctionalInterface} are
* {@link Value#execute(Object...) executable} directly. Java {@link Class} instances are
* interpreted as {@link Value#canInstantiate() instantiable}, but they do not expose Class
* methods as members.
*
*
* Basic Examples:
*
* The following assertion statements always hold:
*
*
* Context context = Context.create();
* assert context.asValue(null).isNull();
* assert context.asValue(42).isNumber();
* assert context.asValue("42").isString();
* assert context.asValue('c').isString();
* assert context.asValue(new String[0]).hasArrayElements();
* assert context.asValue(new ArrayList<>()).isHostObject();
* assert context.asValue(new ArrayList<>()).hasArrayElements();
* assert context.asValue((Supplier) () -> 42).execute().asInt() == 42;
*
*
* Mapping to Java methods and fields
*
* When Java host objects are passed to guest languages, their public methods and fields are
* provided as {@link Value#getMember(String) members}. Methods and fields are grouped by name,
* so only one member is exposed for each name.
*
* When an argument value needs to be mapped to match a required Java method parameter type then
* the semantics of {@link Value#as(Class) host value mapping} is used. The result of the
* mapping is equivalent of calling {@link Value#as(Class)} with the parameter type. Therefore a
* {@link ClassCastException} or {@link NullPointerException} is thrown if a parameter value
* cannot be cast to the required parameter type.
*
* Overloaded java methods are selected based on the arguments that are provided. In case
* multiple mapped Java methods with the same name are applicable for
* {@link Value#execute(Object...) executions} or {@link Value#newInstance(Object...)
* instantiations} then the method with the most concrete method with applicable arguments will
* be used used.
*
* The following parameter type hierarchy is used for method resolution. Left-most parameter
* types are prioritized over types to their right.
*
* - {@link Value#isBoolean() Boolean} values: boolean, Boolean, Object
*
- String values: char, Character, String, CharSequence, Object
*
- Number values: byte, Byte, short, Short, int, Integer, long, Long, float, Float, double,
* Double, Number, Object
*
- Other values are resolved based on their Java type hierarchy.
*
* If there are multiple most concrete methods or too many arguments were provided then an
* illegal argument type error will be raised.
*
* Advanced Example:
*
* This example first creates a new instance of the Java class Record and inspects
* it first using the polyglot value API and later using the JavaScript guest language.
*
* In the following examples all assertions hold.
*
*
* class JavaRecord {
* public int x = 42;
* public double y = 42.0;
* public String name() {
* return "foo";
* }
* }
* Context context = Context.create();
* Value record = context.asValue(new JavaRecord());
* assert record.getMember("x").asInt() == 42;
* assert record.getMember("y").asDouble() == 42.0d;
* assert record.getMember("name").execute().asString().equals("foo");
*
* assert context.eval("js", "(function(record) record.x)")
* .execute(record).asInt() == 42;
* assert context.eval("js", "(function(record) record.y)")
* .execute(record).asDouble() == 42.0d;
* assert context.eval("js", "(function(record) record.name())")
* .execute(record).asString().equals("foo");
*
*
* @see Value#as(Class)
* @throws IllegalStateException if the context is already closed
* @param hostValue the host value to convert to a polyglot value.
* @return the polyglot value.
* @since 1.0
*/
public Value asValue(Object hostValue) {
return impl.asValue(hostValue);
}
/**
* Explicitly enters this context on the current thread. A context needs to be entered for any
* operation to be performed. The context implicitly enters and leaves the context for every
* operation. For example, before and after invoking the {@link Value#execute(Object...)
* execute} method. This can be inefficient if a very high number of simple operations needs to
* be performed. By {@link #enter() entering} and {@link #leave() leaving} once explicitly, the
* overhead for entering/leaving contexts for each operation can be eliminated. Contexts can be
* entered multiple times on the same thread.
*
* @throws IllegalStateException if the context is already {@link #close() closed}.
* @throws PolyglotException if a language has denied execution on the current thread.
* @see #leave() to leave a context.
* @since 1.0
*/
public void enter() {
impl.explicitEnter(this);
}
/**
* Explicitly leaves this context on the current thread. The context must be {@link #enter()
* entered} before calling this method.
*
* @throws IllegalStateException if the context is already closed or if the context was not
* {@link #enter() entered} on the current thread.
* @see #enter() to enter a context.
* @since 1.0
*/
public void leave() {
impl.explicitLeave(this);
}
/**
* Closes this context and frees up potentially allocated native resources. A context cannot
* free all native resources allocated automatically. For this reason it is necessary to close
* contexts after use. If a context is cancelled then the currently executing thread will throw
* a {@link PolyglotException}. The exception indicates that it was
* {@link PolyglotException#isCancelled() cancelled}. Please note that canceling a single
* context can negatively affect the performance of other executing contexts constructed with
* the same engine.
*
* If internal errors occur during closing of the language then they are printed to the
* configured {@link Builder#err(OutputStream) error output stream}. If a context was closed
* then all its methods will throw an {@link IllegalStateException} when invoked. If an attempt
* to close a context was successful then consecutive calls to close have no effect.
*
* @param cancelIfExecuting if true then currently executing contexts will be
* {@link PolyglotException#isCancelled() cancelled}, else an
* {@link IllegalStateException} is thrown.
* @see Engine#close() To close an engine.
* @throws PolyglotException in case the close failed due to a guest language error.
* @throws IllegalStateException if the context is still running and cancelIfExecuting is
* false
* @since 1.0
*/
public void close(boolean cancelIfExecuting) {
impl.close(this, cancelIfExecuting);
}
/**
* Closes this context and frees up potentially allocated native resources. Languages might not
* be able to free all native resources allocated by a context automatically. For this reason it
* is recommended to close contexts after use. If the context is currently being executed on
* another thread then an {@link IllegalStateException} is thrown. To close concurrently
* executing contexts see {@link #close(boolean)}.
*
* If internal errors occur during closing of the language then they are printed to the
* configured {@link Builder#err(OutputStream) error output stream}. If a context was closed
* then all its methods will throw an {@link IllegalStateException} when invoked. If an attempt
* to close a context was successful then consecutive calls to close have no effect.
*
* @throws PolyglotException in case the close failed due to a guest language error.
* @throws IllegalStateException if the context is currently executing on another thread.
* @see Engine#close() To close an engine.
* @since 1.0
*/
public void close() {
close(false);
}
/**
* Returns the currently entered polyglot context. A context is entered if the currently
* executing Java method was called by a Graal guest language or if a context was entered
* explicitly using {@link Context#enter()} on the current thread. The returned context may be
* used to:
*
* - Evaluate guest language code from {@link #eval(String, CharSequence) string literals} or
* {@link #eval(Source) file} sources.
*
- {@link #asValue(Object) Convert} Java values to {@link Value polyglot values}.
*
- Access top-level {@link #getBindings(String) bindings} of other languages.
*
- Access {@link #getPolyglotBindings() polyglot bindings}.
*
- Access meta-data like available {@link Engine#getLanguages() languages} or
* {@link Engine#getOptions() options} of the {@link #getEngine() engine}.
*
*
* The returned context may not be used to {@link #enter() enter} , {@link #leave()
* leave} or {@link #close() close} the context or {@link #getEngine() engine}. Invoking such
* methods will cause an {@link IllegalStateException} to be thrown. This ensures that only the
* {@link #create(String...) creator} of a context is allowed to enter, leave or close a
* context.
*
* The currently entered context may change. It is therefore required to call
* {@link #getCurrent() getCurrent} every time a context is needed. The currently entered
* context should not be cached in static fields.
*
* @throws IllegalStateException if no context is currently entered.
* @since 1.0
*/
public static Context getCurrent() {
return Engine.getImpl().getCurrentContext();
}
/**
* Creates a context with default configuration.
*
* @param permittedLanguages names of languages permitted in this context, if no languages are
* provided then all the use of languages will be permitted.
* @return a new context
* @since 1.0
*/
public static Context create(String... permittedLanguages) {
return newBuilder(permittedLanguages).build();
}
/**
* Creates a builder for constructing a context with custom configuration.
*
* @param permittedLanguages names of languages permitted in this context, if no languages are
* provided then the use of all languages will be permitted.
* @return a builder that can create a context
* @since 1.0
*/
public static Builder newBuilder(String... permittedLanguages) {
return EMPTY.new Builder(permittedLanguages);
}
private static final Context EMPTY = new Context(null);
/**
* Builder class to construct {@link Context} instances. A builder instance is not thread-safe
* and must not be used from multiple threads at the same time.
*
* @see Context
* @since 1.0
*/
@SuppressWarnings("hiding")
public final class Builder {
private Engine sharedEngine;
private String[] onlyLanguages;
private OutputStream out;
private OutputStream err;
private InputStream in;
private Map options;
private Map arguments;
private Predicate hostClassFilter;
private Boolean allowHostAccess;
private Boolean allowNativeAccess;
private Boolean allowCreateThread;
private boolean allowAllAccess;
private Boolean allowIO;
private Boolean allowHostClassLoading;
private FileSystem customFileSystem;
private Handler customLogHandler;
Builder(String... onlyLanguages) {
Objects.requireNonNull(onlyLanguages);
for (String onlyLanguage : onlyLanguages) {
Objects.requireNonNull(onlyLanguage);
}
this.onlyLanguages = onlyLanguages;
}
/**
* Explicitly sets the underlying engine to use. By default every context has its own
* isolated engine. If multiple contexts are created from one engine, then they may
* share/cache certain system resources like ASTs, optimized code by specifying a single
* underlying engine; see {@link Engine} for more details about system resource sharing.
*
* @since 1.0
*/
public Builder engine(Engine engine) {
Objects.requireNonNull(engine);
this.sharedEngine = engine;
return this;
}
/**
* Sets the standard output stream to be used for this context. If not set then the standard
* output stream configured for the {@link #engine(Engine) engine} is used or standard error
* stream.
*
* @since 1.0
*/
public Builder out(OutputStream out) {
Objects.requireNonNull(out);
this.out = out;
return this;
}
/**
* Sets the error output stream to be used for this context. If not set then either the
* error stream configured for the {@link #engine(Engine) engine} is used or standard error
* stream.
*
* @since 1.0
*/
public Builder err(OutputStream err) {
Objects.requireNonNull(err);
this.err = err;
return this;
}
/**
* Sets the input stream to be used for this context. If not set then either the input
* stream configured for the {@link #engine(Engine) engine} is used or standard in stream.
*
* @since 1.0
*/
public Builder in(InputStream in) {
Objects.requireNonNull(in);
this.in = in;
return this;
}
/**
* Allows guest languages to access the host language by loading new classes. Default is
* false. If {@link #allowAllAccess(boolean) all access} is set to
* true then then host access is enabled if not allowed explicitly.
*
* @since 1.0
*/
public Builder allowHostAccess(boolean enabled) {
this.allowHostAccess = enabled;
return this;
}
/**
* Allows guest languages to access the native interface.
*
* @since 1.0
*/
public Builder allowNativeAccess(boolean enabled) {
this.allowNativeAccess = enabled;
return this;
}
/**
* If true allows guest languages to create new threads. Default is
* false. If {@link #allowAllAccess(boolean) all access} is set to
* true then the creation of threads is enabled if not allowed explicitly.
* Threads created by guest languages are closed when the context is {@link Context#close()
* closed}.
*
* @since 1.0
*/
public Builder allowCreateThread(boolean enabled) {
this.allowCreateThread = enabled;
return this;
}
/**
* If true grants the context the same access privileges as the host virtual
* machine. If not explicitly specified then all access is false. If the host
* VM runs without a {@link SecurityManager security manager} enabled, then enabling all
* access gives the guest languages full control over the host process. Otherwise, the Java
* {@link SecurityManager security manager} is in control of restricting the privileges of
* the polyglot context. If new privilege restrictions are added to the polyglot API then
* they will default to full access if all access is set to true. If all access
* is enabled then certain privileges may still be disabled by configuring it explicitly
* using this builder.
*
* Grants full access to the following privileges by default:
*
* - The {@link #allowCreateThread(boolean) creation} and use of new threads.
*
- The access to public {@link #allowHostAccess(boolean) host classes}.
*
- The loading of new {@link #allowHostClassLoading(boolean) host classes} by adding
* entries to the class path.
*
- Exporting new members into the polyglot {@link Context#getPolyglotBindings()
* bindings}.
*
- Unrestricted {@link #allowIO(boolean) IO operations} on host system.
*
*
* @param enabled true for all access by default.
* @since 1.0
*/
public Builder allowAllAccess(boolean enabled) {
this.allowAllAccess = enabled;
return this;
}
/**
* If host class loading is enabled then the guest language is allowed to load new host
* classes via jar or class files. If {@link #allowAllAccess(boolean) all access} is set to
* true then the host class loading is enabled if it is not disallowed
* explicitly. For host class loading to be useful {@link #allowIO(boolean) IO} operations
* and {@link #allowHostAccess(boolean) host access} need to be allowed as well.
*
* @since 1.0
*/
public Builder allowHostClassLoading(boolean enabled) {
this.allowHostClassLoading = enabled;
return this;
}
/**
* Sets a class filter that allows to limit the classes that are allowed to be loaded by
* guest languages. If the filter returns true then the class is accessible,
* else it is not accessible and throws an guest language error when accessed. In order to
* have an effect {@link #allowHostAccess(boolean)} or {@link #allowAllAccess(boolean)}
* needs to be set to true.
*
* @param classFilter a predicate that returns true or false for a
* java qualified class name.
* @since 1.0
*/
public Builder hostClassFilter(Predicate classFilter) {
Objects.requireNonNull(classFilter);
this.hostClassFilter = classFilter;
return this;
}
/**
* Set an option for this {@link Context context}. By default any options for the
* {@link Engine#getOptions() engine}, {@link Language#getOptions() language} or
* {@link Instrument#getOptions() instrument} can be set for a context. If an
* {@link #engine(Engine) explicit engine} is set for this context then only language
* options can be set. Instrument and engine options can be set exclusively on the explicit
* engine instance. If a language option was set for the context and the engine then the
* option of the context is going to take precedence.
*
* If one of the set option keys or values is invalid then an
* {@link IllegalArgumentException} is thrown when the context is {@link #build() built}.
* The given key and value must not be null.
*
* @see Engine.Builder#option(String, String) To specify an option for the engine.
* @since 1.0
*/
public Builder option(String key, String value) {
Objects.requireNonNull(key);
Objects.requireNonNull(value);
if (this.options == null) {
this.options = new HashMap<>();
}
this.options.put(key, value);
return this;
}
/**
* Shortcut for setting multiple {@link #option(String, String) options} using a map. All
* values of the provided map must be non-null.
*
* @param options a map options.
* @see #option(String, String) To set a single option.
* @since 1.0
*/
public Builder options(Map options) {
for (String key : options.keySet()) {
option(key, options.get(key));
}
return this;
}
/**
* Sets the guest language application arguments for a language {@link Context context}.
* Application arguments are typically made available to guest language implementations. It
* depends on the language if and how they are accessible within the
* {@link Context#eval(Source) evaluated} guest language scripts. Passing no arguments to a
* language is equivalent to providing an empty arguments array.
*
* @param language the language id of the primary language.
* @param args an array of arguments passed to the guest language program.
* @throws IllegalArgumentException if an invalid language id was specified.
* @since 1.0
*/
public Builder arguments(String language, String[] args) {
Objects.requireNonNull(language);
Objects.requireNonNull(args);
String[] newArgs = args;
if (args.length > 0) {
newArgs = new String[args.length];
for (int i = 0; i < args.length; i++) { // defensive copy
newArgs[i] = Objects.requireNonNull(args[i]);
}
}
if (arguments == null) {
arguments = new HashMap<>();
}
arguments.put(language, newArgs);
return this;
}
/**
* If true allows guest language to perform unrestricted IO operations on host
* system. Default is false. If {@link #allowAllAccess(boolean) all access} is
* set to true then IO is enabled if not allowed explicitly.
*
* @param enabled {@code true} to enable Input/Output
* @return the {@link Builder}
* @since 1.0
*/
public Builder allowIO(final boolean enabled) {
allowIO = enabled;
return this;
}
/**
* Installs a new {@link FileSystem}.
*
* @param fileSystem the file system to be installed
* @return the {@link Builder}
* @since 1.0
*/
public Builder fileSystem(final FileSystem fileSystem) {
Objects.requireNonNull(fileSystem, "FileSystem must be non null.");
this.customFileSystem = fileSystem;
return this;
}
/**
* Installs a new logging {@link Handler}. The logger's {@link Level} configuration is done
* using the {@link #options(java.util.Map) Context's options}. The level option key has the
* following format: {@code log.languageId.loggerName.level} or
* {@code log.instrumentId.loggerName.level}. The value is either the name of pre-defined
* {@link Level} constant or a numeric {@link Level} value. If not explicitly set in options
* the level is inherited from the parent logger.
*
* Examples of setting log level options:
* {@code builder.option("log.level","FINE");} sets the {@link Level#FINE FINE level} to all
* {@code TruffleLogger}s.
* {@code builder.option("log.js.level","FINE");} sets the {@link Level#FINE FINE level} to
* JavaScript {@code TruffleLogger}s.
* {@code builder.option("log.js.com.oracle.truffle.js.parser.JavaScriptLanguage.level","FINE");}
* sets the {@link Level#FINE FINE level} to {@code TruffleLogger} for the
* {@code JavaScriptLanguage} class.
*
* If the {@code logHandler} is not set on {@link Engine} nor on {@link Context} the log
* messages are printed to {@link #out(java.io.OutputStream) Context's standard output
* stream}.
*
* @param logHandler the {@link Handler} to use for logging in built {@link Context}.
* @return the {@link Builder}
* @since 1.0
*/
public Builder logHandler(final Handler logHandler) {
Objects.requireNonNull(logHandler, "Hanlder must be non null.");
this.customLogHandler = logHandler;
return this;
}
/**
* Creates a new context instance from the configuration provided in the builder. The same
* context builder can be used to create multiple context instances.
*
* @since 1.0
*/
public Context build() {
if (allowHostAccess == null) {
allowHostAccess = allowAllAccess;
}
if (allowNativeAccess == null) {
allowNativeAccess = allowAllAccess;
}
if (allowCreateThread == null) {
allowCreateThread = allowAllAccess;
}
if (allowIO == null) {
allowIO = allowAllAccess;
}
if (allowHostClassLoading == null) {
allowHostClassLoading = allowAllAccess;
}
if (!allowIO && customFileSystem != null) {
throw new IllegalStateException("Cannot install custom FileSystem when IO is disabled.");
}
Engine engine = this.sharedEngine;
if (engine == null) {
org.graalvm.polyglot.Engine.Builder engineBuilder = Engine.newBuilder().options(options == null ? Collections.emptyMap() : options);
if (out != null) {
engineBuilder.out(out);
}
if (err != null) {
engineBuilder.err(err);
}
if (in != null) {
engineBuilder.in(in);
}
if (customLogHandler != null) {
engineBuilder.logHandler(customLogHandler);
}
engineBuilder.setBoundEngine(true);
engine = engineBuilder.build();
return engine.impl.createContext(null, null, null, allowHostAccess, allowNativeAccess, allowCreateThread, allowIO,
allowHostClassLoading,
hostClassFilter, Collections.emptyMap(), arguments == null ? Collections.emptyMap() : arguments, onlyLanguages, customFileSystem, customLogHandler);
} else {
return engine.impl.createContext(out, err, in, allowHostAccess, allowNativeAccess, allowCreateThread, allowIO,
allowHostClassLoading,
hostClassFilter, options == null ? Collections.emptyMap() : options, arguments == null ? Collections.emptyMap() : arguments, onlyLanguages, customFileSystem,
customLogHandler);
}
}
}
}