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/*
* JBoss, Home of Professional Open Source.
* Copyright 2017 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wildfly.common.expression;
import java.util.ArrayList;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.function.BiConsumer;
import org.wildfly.common.Assert;
import org.wildfly.common._private.CommonMessages;
import org.wildfly.common.function.ExceptionBiConsumer;
/**
* A compiled property-expansion expression string. An expression string is a mix of plain strings and expression
* segments, which are wrapped by the sequence "{@code ${ ... }}".
*
* @author David M. Lloyd
*/
public final class Expression {
private final Node content;
private final Set referencedStrings;
Expression(Node content) {
this.content = content;
HashSet strings = new HashSet<>();
content.catalog(strings);
referencedStrings = strings.isEmpty() ? Collections.emptySet() : strings.size() == 1 ? Collections.singleton(strings.iterator().next()) : Collections.unmodifiableSet(strings);
}
/**
* Get the immutable set of string keys that are referenced by expressions in this compiled expression. If there
* are no expansions in this expression, the set is empty. Note that this will not include any string keys
* that themselves contain expressions, in the case that {@link Flag#NO_RECURSE_KEY} was not specified.
*
* @return the immutable set of strings (not {@code null})
*/
public Set getReferencedStrings() {
return referencedStrings;
}
/**
* Evaluate the expression with the given expansion function, which may throw a checked exception. The given "function"
* is a predicate which returns {@code true} if the expansion succeeded or {@code false} if it failed (in which case
* a default value may be used). If expansion succeeds, the expansion function should append the result to the
* given {@link StringBuilder}.
*
* @param expandFunction the expansion function to apply (must not be {@code null})
* @param the exception type thrown by the expansion function
* @return the expanded string
* @throws E if the expansion function throws an exception
*/
public String evaluateException(final ExceptionBiConsumer, StringBuilder, E> expandFunction) throws E {
Assert.checkNotNullParam("expandFunction", expandFunction);
final StringBuilder b = new StringBuilder();
content.emit(new ResolveContext(expandFunction, b), expandFunction);
return b.toString();
}
/**
* Evaluate the expression with the given expansion function. The given "function"
* is a predicate which returns {@code true} if the expansion succeeded or {@code false} if it failed (in which case
* a default value may be used). If expansion succeeds, the expansion function should append the result to the
* given {@link StringBuilder}.
*
* @param expandFunction the expansion function to apply (must not be {@code null})
* @return the expanded string
*/
public String evaluate(BiConsumer, StringBuilder> expandFunction) {
return evaluateException(expandFunction::accept);
}
/**
* Evaluate the expression using a default expansion function that evaluates system and environment properties
* in the JBoss style (i.e. using the prefix {@code "env."} to designate an environment property).
* The caller must have all required security manager permissions.
*
* @param failOnNoDefault {@code true} to throw an {@link IllegalArgumentException} if an unresolvable key has no
* default value; {@code false} to expand such keys to an empty string
* @return the expanded string
*/
public String evaluateWithPropertiesAndEnvironment(boolean failOnNoDefault) {
return evaluate((c, b) -> {
final String key = c.getKey();
if (key.startsWith("env.")) {
final String env = key.substring(4);
final String val = System.getenv(env);
if (val == null) {
if (failOnNoDefault && ! c.hasDefault()) {
throw CommonMessages.msg.unresolvedEnvironmentProperty(env);
}
c.expandDefault();
} else {
b.append(val);
}
} else {
final String val = System.getProperty(key);
if (val == null) {
if (failOnNoDefault && ! c.hasDefault()) {
throw CommonMessages.msg.unresolvedSystemProperty(key);
}
c.expandDefault();
} else {
b.append(val);
}
}
});
}
/**
* Evaluate the expression using a default expansion function that evaluates system properties.
* The caller must have all required security manager permissions.
*
* @param failOnNoDefault {@code true} to throw an {@link IllegalArgumentException} if an unresolvable key has no
* default value; {@code false} to expand such keys to an empty string
* @return the expanded string
*/
public String evaluateWithProperties(boolean failOnNoDefault) {
return evaluate((c, b) -> {
final String key = c.getKey();
final String val = System.getProperty(key);
if (val == null) {
if (failOnNoDefault && ! c.hasDefault()) {
throw CommonMessages.msg.unresolvedSystemProperty(key);
}
c.expandDefault();
} else {
b.append(val);
}
});
}
/**
* Evaluate the expression using a default expansion function that evaluates environment properties.
* The caller must have all required security manager permissions.
*
* @param failOnNoDefault {@code true} to throw an {@link IllegalArgumentException} if an unresolvable key has no
* default value; {@code false} to expand such keys to an empty string
* @return the expanded string
*/
public String evaluateWithEnvironment(boolean failOnNoDefault) {
return evaluate((c, b) -> {
final String key = c.getKey();
final String val = System.getenv(key);
if (val == null) {
if (failOnNoDefault && ! c.hasDefault()) {
throw CommonMessages.msg.unresolvedEnvironmentProperty(key);
}
c.expandDefault();
} else {
b.append(val);
}
});
}
/**
* Compile an expression string.
*
* @param string the expression string (must not be {@code null})
* @param flags optional flags to apply which affect the compilation
* @return the compiled expression (not {@code null})
*/
public static Expression compile(String string, Flag... flags) {
return compile(string, flags == null || flags.length == 0 ? NO_FLAGS : EnumSet.of(flags[0], flags));
}
/**
* Compile an expression string.
*
* @param string the expression string (must not be {@code null})
* @param flags optional flags to apply which affect the compilation (must not be {@code null})
* @return the compiled expression (not {@code null})
*/
public static Expression compile(String string, EnumSet flags) {
Assert.checkNotNullParam("string", string);
Assert.checkNotNullParam("flags", flags);
final Node content;
final Itr itr;
if (flags.contains(Flag.NO_TRIM)) {
itr = new Itr(string);
} else {
itr = new Itr(string.trim());
}
content = parseString(itr, true, false, false, flags);
return content == Node.NULL ? EMPTY : new Expression(content);
}
private static final Expression EMPTY = new Expression(Node.NULL);
static final class Itr {
private final String str;
private int idx;
Itr(final String str) {
this.str = str;
}
boolean hasNext() {
return idx < str.length();
}
int next() {
final int idx = this.idx;
try {
return str.codePointAt(idx);
} finally {
this.idx = str.offsetByCodePoints(idx, 1);
}
}
int prev() {
final int idx = this.idx;
try {
return str.codePointBefore(idx);
} finally {
this.idx = str.offsetByCodePoints(idx, -1);
}
}
int getNextIdx() {
return idx;
}
int getPrevIdx() {
return str.offsetByCodePoints(idx, -1);
}
String getStr() {
return str;
}
int peekNext() {
return str.codePointAt(idx);
}
int peekPrev() {
return str.codePointBefore(idx);
}
void rewind(final int newNext) {
idx = newNext;
}
}
private static Node parseString(Itr itr, final boolean allowExpr, final boolean endOnBrace, final boolean endOnColon, final EnumSet flags) {
int ignoreBraceLevel = 0;
final List list = new ArrayList<>();
int start = itr.getNextIdx();
while (itr.hasNext()) {
// index of this character
int idx = itr.getNextIdx();
int ch = itr.next();
switch (ch) {
case '$': {
if (! allowExpr) {
// TP 1
// treat as plain content
continue;
}
// check to see if it's a dangling $
if (! itr.hasNext()) {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 2
throw invalidExpressionSyntax(itr.getStr(), idx);
}
// TP 3
list.add(new LiteralNode(itr.getStr(), start, itr.getNextIdx()));
start = itr.getNextIdx();
continue;
}
// enqueue what we have acquired so far
if (idx > start) {
// TP 4
list.add(new LiteralNode(itr.getStr(), start, idx));
}
// next char should be an expression starter of some sort
idx = itr.getNextIdx();
ch = itr.next();
switch (ch) {
case '{': {
// ${
boolean general = flags.contains(Flag.GENERAL_EXPANSION) && itr.hasNext() && itr.peekNext() == '{';
// consume double-{
if (general) itr.next();
// set start to the beginning of the key for later
start = itr.getNextIdx();
// the expression name starts in the next position
Node keyNode = parseString(itr, ! flags.contains(Flag.NO_RECURSE_KEY), true, true, flags);
if (! itr.hasNext()) {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 5
throw invalidExpressionSyntax(itr.getStr(), itr.getNextIdx());
}
// TP 6
// otherwise treat it as a properly terminated expression
list.add(new ExpressionNode(general, keyNode, Node.NULL));
start = itr.getNextIdx();
continue;
} else if (itr.peekNext() == ':') {
if (flags.contains(Flag.DOUBLE_COLON) && itr.hasNext() && itr.peekNext() == ':') {
// TP 7
// OK actually the whole thing is really going to be part of the key
// Best approach is, rewind and do it over again, but without end-on-colon
itr.rewind(start);
keyNode = parseString(itr, ! flags.contains(Flag.NO_RECURSE_KEY), true, false, flags);
list.add(new ExpressionNode(general, keyNode, Node.NULL));
} else {
// TP 8
itr.next(); // consume it
final Node defaultValueNode = parseString(itr, ! flags.contains(Flag.NO_RECURSE_DEFAULT), true, false, flags);
list.add(new ExpressionNode(general, keyNode, defaultValueNode));
}
// now expect }
if (! itr.hasNext()) {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 9
throw invalidExpressionSyntax(itr.getStr(), itr.getNextIdx());
}
// TP 10
// otherwise treat it as a properly terminated expression
start = itr.getNextIdx();
continue;
} else {
// TP 11
assert itr.peekNext() == '}';
itr.next(); // consume
if (general) {
if (! itr.hasNext()) {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 11_1
throw invalidExpressionSyntax(itr.getStr(), itr.getNextIdx());
}
// TP 11_2
// otherwise treat it as a properly terminated expression
start = itr.getNextIdx();
continue;
} else {
if (itr.peekNext() == '}') {
itr.next(); // consume it
// TP 11_3
start = itr.getNextIdx();
continue;
} else {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 11_4
throw invalidExpressionSyntax(itr.getStr(), itr.getNextIdx());
}
// otherwise treat it as a properly terminated expression
start = itr.getNextIdx();
continue;
}
}
} else {
start = itr.getNextIdx();
continue;
}
//throw Assert.unreachableCode();
}
} else {
// TP 12
assert itr.peekNext() == '}';
itr.next(); // consume
list.add(new ExpressionNode(general, keyNode, Node.NULL));
if (general) {
if (! itr.hasNext()) {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 12_1
throw invalidExpressionSyntax(itr.getStr(), itr.getNextIdx());
}
// TP 12_2
// otherwise treat it as a properly terminated expression
start = itr.getNextIdx();
continue;
} else {
if (itr.peekNext() == '}') {
itr.next(); // consume it
// TP 12_3
start = itr.getNextIdx();
continue;
} else {
if (! flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 12_4
throw invalidExpressionSyntax(itr.getStr(), itr.getNextIdx());
}
// otherwise treat it as a properly terminated expression
start = itr.getNextIdx();
continue;
}
}
}
start = itr.getNextIdx();
continue;
}
//throw Assert.unreachableCode();
}
case '$': {
// $$
if (flags.contains(Flag.MINI_EXPRS)) {
// TP 13
list.add(new ExpressionNode(false, LiteralNode.DOLLAR, Node.NULL));
} else {
// just resolve $$ to $
// TP 14
list.add(LiteralNode.DOLLAR);
}
start = itr.getNextIdx();
continue;
}
case '}': {
// $}
if (flags.contains(Flag.MINI_EXPRS)) {
// TP 15
list.add(new ExpressionNode(false, LiteralNode.CLOSE_BRACE, Node.NULL));
start = itr.getNextIdx();
continue;
} else if (endOnBrace) {
if (flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 16
// just treat the $ that we got like plain text, and return
list.add(LiteralNode.DOLLAR);
itr.prev(); // back up to point at } again
return Node.fromList(list);
} else {
// TP 17
throw invalidExpressionSyntax(itr.getStr(), idx);
}
} else {
if (flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 18
// just treat $} like plain text
list.add(LiteralNode.DOLLAR);
list.add(LiteralNode.CLOSE_BRACE);
start = itr.getNextIdx();
continue;
} else {
// TP 19
throw invalidExpressionSyntax(itr.getStr(), idx);
}
}
//throw Assert.unreachableCode();
}
case ':': {
// $:
if (flags.contains(Flag.MINI_EXPRS)) {
// $: is an expression
// TP 20
list.add(new ExpressionNode(false, LiteralNode.COLON, Node.NULL));
start = itr.getNextIdx();
continue;
} else if (endOnColon) {
if (flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 21
// just treat the $ that we got like plain text, and return
itr.prev(); // back up to point at : again
list.add(LiteralNode.DOLLAR);
return Node.fromList(list);
} else {
// TP 22
throw invalidExpressionSyntax(itr.getStr(), idx);
}
} else {
if (flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 23
// just treat $: like plain text
list.add(LiteralNode.DOLLAR);
list.add(LiteralNode.COLON);
start = itr.getNextIdx();
continue;
} else {
// TP 24
throw invalidExpressionSyntax(itr.getStr(), idx);
}
}
//throw Assert.unreachableCode();
}
default: {
// $ followed by anything else
if (flags.contains(Flag.MINI_EXPRS)) {
// TP 25
list.add(new ExpressionNode(false, new LiteralNode(itr.getStr(), idx, itr.getNextIdx()), Node.NULL));
start = itr.getNextIdx();
continue;
} else if (flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 26
// just treat it as literal
start = itr.getPrevIdx() - 1; // we can use 1 here because unicode '$' is one char in size
continue;
} else {
// TP 27
throw invalidExpressionSyntax(itr.getStr(), idx);
}
//throw Assert.unreachableCode();
}
}
//throw Assert.unreachableCode();
}
case ':': {
if (endOnColon) {
// TP 28
itr.prev(); // back up to point at : again
if (idx > start) {
list.add(new LiteralNode(itr.getStr(), start, idx));
}
return Node.fromList(list);
} else {
// TP 29
// plain content always
continue;
}
//throw Assert.unreachableCode();
}
case '{': {
if (! flags.contains(Flag.NO_SMART_BRACES)) {
// TP 1.2
ignoreBraceLevel++;
}
// TP 1.3
continue;
}
case '}': {
if (! flags.contains(Flag.NO_SMART_BRACES) && ignoreBraceLevel > 0) {
// TP 1.1
ignoreBraceLevel--;
continue;
} else if (endOnBrace) {
// TP 30
itr.prev(); // back up to point at } again
if (idx > start) {
list.add(new LiteralNode(itr.getStr(), start, idx));
}
return Node.fromList(list);
} else {
// TP 31
// treat as plain content
continue;
}
//throw Assert.unreachableCode();
}
case '\\': {
if (flags.contains(Flag.ESCAPES)) {
if (idx > start) {
list.add(new LiteralNode(itr.getStr(), start, idx));
start = idx;
}
if (! itr.hasNext()) {
if (flags.contains(Flag.LENIENT_SYNTAX)) {
// just treat it like plain content
// TP 33
continue;
} else {
// TP 34
throw invalidExpressionSyntax(itr.getStr(), idx);
}
} else {
ch = itr.next();
final LiteralNode node;
switch (ch) {
case 'n': {
// TP 35
node = LiteralNode.NEWLINE;
break;
}
case 'r': {
// TP 36
node = LiteralNode.CARRIAGE_RETURN;
break;
}
case 't': {
// TP 37
node = LiteralNode.TAB;
break;
}
case 'b': {
// TP 38
node = LiteralNode.BACKSPACE;
break;
}
case 'f': {
// TP 39
node = LiteralNode.FORM_FEED;
break;
}
case '\\': {
// TP 45
node = LiteralNode.BACKSLASH;
break;
}
default: {
if (flags.contains(Flag.LENIENT_SYNTAX)) {
// TP 40
// just append the literal character after the \, whatever it was
start = itr.getPrevIdx();
continue;
}
// TP 41
throw invalidExpressionSyntax(itr.getStr(), idx);
}
}
list.add(node);
start = itr.getNextIdx();
continue;
}
}
// TP 42
// otherwise, just...
continue;
}
default: {
// TP 43
// treat as plain content
//noinspection UnnecessaryContinue
continue;
}
}
//throw Assert.unreachableCode();
}
final int length = itr.getStr().length();
if (length > start) {
// TP 44
list.add(new LiteralNode(itr.getStr(), start, length));
}
return Node.fromList(list);
}
private static IllegalArgumentException invalidExpressionSyntax(final String string, final int index) {
String msg = CommonMessages.msg.invalidExpressionSyntax(index);
StringBuilder b = new StringBuilder(msg.length() + string.length() + string.length() + 5);
b.append(msg);
b.append('\n').append('\t').append(string);
b.append('\n').append('\t');
for (int i = 0; i < index; i = string.offsetByCodePoints(i, 1)) {
final int cp = string.codePointAt(i);
if (Character.isWhitespace(cp)) {
b.append(cp);
} else if (Character.isValidCodePoint(cp) && ! Character.isISOControl(cp)) {
b.append(' ');
}
}
b.append('^');
return new IllegalArgumentException(b.toString());
}
private static final EnumSet NO_FLAGS = EnumSet.noneOf(Flag.class);
/**
* Flags that can apply to a property expression compilation
*/
public enum Flag {
/**
* Do not trim leading and trailing whitespace off of the expression string before parsing it.
*/
NO_TRIM,
/**
* Ignore syntax problems instead of throwing an exception.
*/
LENIENT_SYNTAX,
/**
* Support single-character expressions that can be interpreted without wrapping in curly braces.
*/
MINI_EXPRS,
/**
* Do not support recursive expression expansion in the key part of the expression.
*/
NO_RECURSE_KEY,
/**
* Do not support recursion in default values.
*/
NO_RECURSE_DEFAULT,
/**
* Do not support smart braces.
*/
NO_SMART_BRACES,
/**
* Support {@code Policy} file style "general" expansion alternate expression syntax. "Smart" braces
* will only work if the opening brace is not the first character in the expression key.
*/
GENERAL_EXPANSION,
/**
* Support standard escape sequences in plain text and default value fields, which begin with a backslash ("{@code \}") character.
*/
ESCAPES,
/**
* Treat expressions containing a double-colon delimiter as special, encoding the entire content into the key.
*/
DOUBLE_COLON,
}
}
