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/**
* Copyright (c) 2014 SQUARESPACE, Inc.
*
* 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 com.squarespace.template;
import static com.squarespace.template.Patterns.EOF_CHAR;
import static com.squarespace.template.Patterns.META_LEFT_CHAR;
import static com.squarespace.template.Patterns.META_RIGHT_CHAR;
import static com.squarespace.template.Patterns.NEWLINE_CHAR;
import static com.squarespace.template.Patterns.POUND_CHAR;
import static com.squarespace.template.SyntaxErrorType.BINDVAR_EXPECTS_NAME;
import static com.squarespace.template.SyntaxErrorType.CTXVAR_EXPECTS_BINDINGS;
import static com.squarespace.template.SyntaxErrorType.CTXVAR_EXPECTS_NAME;
import static com.squarespace.template.SyntaxErrorType.EXTRA_CHARS;
import static com.squarespace.template.SyntaxErrorType.FORMATTER_ARGS_INVALID;
import static com.squarespace.template.SyntaxErrorType.FORMATTER_INVALID;
import static com.squarespace.template.SyntaxErrorType.FORMATTER_NEEDS_ARGS;
import static com.squarespace.template.SyntaxErrorType.FORMATTER_UNKNOWN;
import static com.squarespace.template.SyntaxErrorType.IF_EMPTY;
import static com.squarespace.template.SyntaxErrorType.IF_EXPECTED_VAROP;
import static com.squarespace.template.SyntaxErrorType.IF_TOO_MANY_OPERATORS;
import static com.squarespace.template.SyntaxErrorType.IF_TOO_MANY_VARS;
import static com.squarespace.template.SyntaxErrorType.INJECT_EXPECTS_NAME;
import static com.squarespace.template.SyntaxErrorType.INJECT_EXPECTS_PATH;
import static com.squarespace.template.SyntaxErrorType.INVALID_INSTRUCTION;
import static com.squarespace.template.SyntaxErrorType.MACRO_EXPECTS_NAME;
import static com.squarespace.template.SyntaxErrorType.MISSING_SECTION_KEYWORD;
import static com.squarespace.template.SyntaxErrorType.MISSING_VARIABLE_NAME;
import static com.squarespace.template.SyntaxErrorType.MISSING_WITH_KEYWORD;
import static com.squarespace.template.SyntaxErrorType.OR_EXPECTED_PREDICATE;
import static com.squarespace.template.SyntaxErrorType.PREDICATE_ARGS_INVALID;
import static com.squarespace.template.SyntaxErrorType.PREDICATE_NEEDS_ARGS;
import static com.squarespace.template.SyntaxErrorType.PREDICATE_UNKNOWN;
import static com.squarespace.template.SyntaxErrorType.VARIABLE_EXPECTED;
import static com.squarespace.template.SyntaxErrorType.WHITESPACE_EXPECTED;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import com.squarespace.template.Instructions.BindVarInst;
import com.squarespace.template.Instructions.CtxVarInst;
import com.squarespace.template.Instructions.EvalInst;
import com.squarespace.template.Instructions.IncludeInst;
import com.squarespace.template.Instructions.InjectInst;
import com.squarespace.template.Instructions.MacroInst;
import com.squarespace.template.Instructions.PredicateInst;
import com.squarespace.template.Instructions.VariableInst;
/**
* Tokenizes characters into instructions, expressing all rules for well-formed
* combinations of instructions.
*
* The Tokenizer is also responsible for the internal composition of an instruction,
* where the CodeMachine is responsible for the overall composition of instructions
* into an executable form.
*
* If a potential instruction sequence cannot be parsed into an instruction, the
* degree to which it matches an instruction pattern is an important factor in
* whether to throw an error or emit the invalid instruction sequence as plain text.
*/
public class Tokenizer {
// Increased at the request of template developers.
private final static int IF_VARIABLE_LIMIT = 30;
private final String raw;
private final int length;
private final CodeSink sink;
private final PredicateTable predicateTable;
private final FormatterTable formatterTable;
private final TokenMatcher matcher;
private final CodeMaker maker;
private State state;
private List errors;
boolean validate = false;
boolean preprocess = false;
private int textLine;
private int textOffset;
private int instLine;
private int instOffset;
private int index = 0;
private int save = 0;
private int metaLeft = -1;
private int lineCounter = 0;
private int lineIndex = 0;
public Tokenizer(
String raw,
CodeSink sink,
FormatterTable formatterTable,
PredicateTable predicateTable) {
this(raw, sink, false, formatterTable, predicateTable);
}
public Tokenizer(
String raw,
CodeSink sink,
boolean preprocess,
FormatterTable formatterTable,
PredicateTable predicateTable) {
this.raw = raw;
this.length = raw.length();
this.sink = sink;
this.preprocess = preprocess;
this.formatterTable = formatterTable;
this.predicateTable = predicateTable;
this.matcher = new TokenMatcher(raw);
this.maker = new CodeMaker();
this.state = stateInitial;
}
public boolean consume() throws CodeSyntaxException {
do {
state = state.transition();
} while (state != stateEOF);
sink.complete();
return (validate) ? errors.size() == 0 : true;
}
/**
* Puts the Tokenizer in a mode where it collects a list of errors, rather than
* throwing an exception on the first parse error.
*/
public void setValidate() {
this.validate = true;
if (this.errors == null) {
this.errors = new ArrayList<>(4);
}
}
public void setPreprocess() {
this.preprocess = true;
}
public List getErrors() {
if (errors == null) {
errors = new ArrayList<>(0);
}
return errors;
}
private char getc(int index) {
return (index < length) ? raw.charAt(index) : Patterns.EOF_CHAR;
}
private void emitInstruction(Instruction inst, boolean preprocessorScope) throws CodeSyntaxException {
inst.setLineNumber(instLine + 1);
inst.setCharOffset(instOffset + 1);
if (preprocessorScope) {
inst.setPreprocessScope();
}
sink.accept(inst);
}
private void emitInstruction(Instruction inst) throws CodeSyntaxException {
emitInstruction(inst, preprocess);
}
private boolean emitInvalid() throws CodeSyntaxException {
sink.accept(maker.text(new StringView(raw, matcher.start() - 1, matcher.end() + 1)));
return true;
}
/**
* Text line numbering is tracked separately from other instructions.
*/
private void emitText(int start, int end) throws CodeSyntaxException {
Instruction inst = maker.text(raw, start, end);
inst.setLineNumber(textLine + 1);
inst.setCharOffset(textOffset + 1);
sink.accept(inst);
}
private ErrorInfo error(SyntaxErrorType code) {
return error(code, 0, false);
}
private ErrorInfo error(SyntaxErrorType code, boolean textLoc) {
return error(code, 0, textLoc);
}
/**
* Include an offset to nudge the error message character offset right to the position of the
* error.
*/
private ErrorInfo error(SyntaxErrorType code, int offset, boolean textLoc) {
ErrorInfo info = new ErrorInfo(code);
info.code(code);
if (textLoc) {
info.line(textLine + 1);
info.offset(textOffset + 1);
} else {
info.line(instLine + 1);
info.offset(instOffset + 1 + offset);
}
return info;
}
private void fail(ErrorInfo info) throws CodeSyntaxException {
if (!validate) {
throw new CodeSyntaxException(info);
}
errors.add(info);
}
/**
* Attempt to parse the meta-delimited chars into an Instruction. The start parameter must
* point to the location of a '{' character in the raw string. The end parameter must
* point 1 character past a '}' character in the raw string, and start must be < end.
*
* Depending on how the parse fails, this may throw a syntax exception. It all depends
* on the degree of ambiguity.
*
* For example if the starting sequence for an instruction is found and the rest is
* invalid, we may throw syntax error. Instead, if the parse is clearly not an instruction
* candidate we ignore the entire sequence and emit a text instruction. An example of
* the latter is if the first character inside the META_LEFT is whitespace. We require
* that instructions begin immediately following the META_LEFT character.
*
* Package-private to facilitate unit testing.
*/
private boolean matchMeta(int start, int end) throws CodeSyntaxException {
if (!(start < end)) {
throw new RuntimeException("Start position should always be less than end. Bug in tokenizer.");
}
// Start token matching everything between '{' and '}'
matcher.region(start + 1, end - 1);
// See if the current instruction is scoped to the pre-processor.
if (matcher.peek(0, '^')) {
// If not in pre-processing mode, skip it.
if (!preprocess) {
return true;
}
matcher.seek(1);
} else if (preprocess) {
// Normal instructions in pre-processing mode are output as text.
return false;
}
// Emit a comment, skipping over the "#".
if (matcher.peek(0, '#')) {
matcher.seek(1);
Instruction comment = maker.comment(raw, matcher.pointer(), matcher.end());
emitInstruction(comment);
return true;
}
return parseKeyword() || parseVariable();
}
/**
* Attempt to parse the range into a keyword instruction.
*/
private boolean parseKeyword() throws CodeSyntaxException {
if (!matcher.keyword()) {
return false;
}
StringView keyword = matcher.consume();
if (keyword.lastChar() == '?') {
Predicate predicate = resolvePredicate(keyword.subview(1, keyword.length()));
Arguments args = parsePredicateArguments(predicate);
if (args == null) {
return emitInvalid();
}
emitInstruction(maker.predicate(predicate, args));
return true;
}
InstructionType type = InstructionTable.get(keyword);
if (type == null) {
fail(error(INVALID_INSTRUCTION).data(keyword));
return emitInvalid();
}
return parseInstruction(type, matcher.pointer(), matcher.end());
}
/**
* We've found the start of an instruction. Parse the rest of the range.
*/
private boolean parseInstruction(InstructionType type, int start, int end) throws CodeSyntaxException {
switch (type) {
case ALTERNATES_WITH:
// Look for SPACE "WITH" EOF
if (!matcher.space()) {
fail(error(SyntaxErrorType.WHITESPACE_EXPECTED).data(matcher.remainder()));
return emitInvalid();
}
matcher.consume();
if (!matcher.wordWith()) {
fail(error(MISSING_WITH_KEYWORD).data(matcher.remainder()));
return emitInvalid();
}
matcher.consume();
if (!matcher.finished()) {
fail(error(EXTRA_CHARS).type(type).data(matcher.remainder()));
return emitInvalid();
}
emitInstruction(maker.alternates());
return true;
case BINDVAR:
{
if (!skipWhitespace()) {
return emitInvalid();
}
// Parse the variable name.
if (!matcher.localVariable()) {
fail(error(BINDVAR_EXPECTS_NAME).data(matcher.remainder()));
return emitInvalid();
}
String name = matcher.consume().repr();
if (!skipWhitespace()) {
return emitInvalid();
}
Variables vars = parseVariables();
if (vars == null) {
fail(error(MISSING_VARIABLE_NAME).data(matcher.remainder()));
return emitInvalid();
}
BindVarInst instruction = maker.bindvar(name, vars);
List formatters = parseFormatters(instruction, start);
if (formatters == null) {
emitInstruction(instruction);
} else if (!formatters.isEmpty()) {
instruction.setFormatters(formatters);
emitInstruction(instruction);
}
return true;
}
case CTXVAR:
{
if (!skipWhitespace()) {
return emitInvalid();
}
// Parse the variable name
if (!matcher.localVariable()) {
fail(error(CTXVAR_EXPECTS_NAME).data(matcher.remainder()));
return emitInvalid();
}
String name = matcher.consume().repr();
if (!skipWhitespace()) {
return emitInvalid();
}
List bindings = parseBindings();
if (bindings == null) {
fail(error(CTXVAR_EXPECTS_BINDINGS).data(matcher.remainder()));
return emitInvalid();
}
CtxVarInst instruction = maker.ctxvar(name, bindings);
emitInstruction(instruction);
return true;
}
case EVAL:
{
if (!skipWhitespace()) {
return emitInvalid();
}
// Instruction has a single argument, a free-form expression
StringView code = matcher.remainder();
// The expression will be parsed and assembled the first time
// the instruction is executed.
EvalInst instruction = maker.eval(code.toString());
emitInstruction(instruction);
return true;
}
case END:
case META_LEFT:
case META_RIGHT:
case NEWLINE:
case SPACE:
case TAB:
// Nothing should follow these instructions.
if (!matcher.finished()) {
fail(error(EXTRA_CHARS).type(type).data(matcher.remainder()));
return emitInvalid();
}
emitInstruction(maker.simple(type));
return true;
case IF:
return parseIfExpression();
case INCLUDE: {
// this instruction accepts space-delimited arguments
if (!matcher.space()) {
return emitInvalid();
}
// TODO: the line below will never fail since it looks for at least 1 character,
// and the matcher is currently pointing at the space above, since it's the
// argument delimiter.
if (!matcher.arguments()) {
return emitInvalid();
}
StringView rawArgs = matcher.consume();
Arguments args = new Arguments(rawArgs);
if (args.count() < 1) {
return emitInvalid();
}
IncludeInst instruction = maker.include(args);
emitInstruction(instruction);
return true;
}
case INJECT:
{
if (!skipWhitespace()) {
return emitInvalid();
}
if (!matcher.localVariable()) {
fail(error(INJECT_EXPECTS_NAME).data(matcher.remainder()));
return emitInvalid();
}
String variable = matcher.consume().repr();
if (!skipWhitespace()) {
return emitInvalid();
}
if (!matcher.path()) {
fail(error(INJECT_EXPECTS_PATH).data(matcher.remainder()));
return emitInvalid();
}
String path = matcher.consume().repr();
StringView rawArgs = null;
Arguments args = Constants.EMPTY_ARGUMENTS;
if (matcher.arguments()) {
rawArgs = matcher.consume();
args = new Arguments(rawArgs);
}
InjectInst instruction = maker.inject(variable, path, args);
emitInstruction(instruction);
return true;
}
case MACRO:
{
if (!skipWhitespace()) {
return emitInvalid();
}
if (!matcher.path()) {
fail(error(MACRO_EXPECTS_NAME));
return emitInvalid();
}
StringView path = matcher.consume();
if (!matcher.finished()) {
fail(error(EXTRA_CHARS).type(type).data(matcher.remainder()));
return emitInvalid();
}
MacroInst inst = maker.macro(path.repr());
emitInstruction(inst);
return true;
}
case OR_PREDICATE:
if (matcher.space()) {
matcher.consume();
if (!matcher.predicate()) {
fail(error(OR_EXPECTED_PREDICATE).type(type).data(matcher.remainder()));
return emitInvalid();
}
Predicate predicate = resolvePredicate(matcher.consume());
Arguments args = parsePredicateArguments(predicate);
if (args == null) {
// Error was emitted by parsePredicateArguments()
return emitInvalid();
}
PredicateInst inst = maker.predicate(predicate, args);
inst.setOr();
emitInstruction(inst);
return true;
}
if (!matcher.finished()) {
fail(error(EXTRA_CHARS).type(type).data(matcher.remainder()));
return emitInvalid();
}
emitInstruction(maker.or());
return true;
case REPEATED:
case SECTION:
return parseSection(type);
default:
throw new RuntimeException("Resolution failure: instruction type '" + type + "' has no text representation.");
}
}
private boolean skipWhitespace() throws CodeSyntaxException {
boolean result = matcher.whitespace();
if (!result) {
fail(error(WHITESPACE_EXPECTED).data(matcher.remainder()));
}
matcher.consume();
return result;
}
/**
* Lookup the keyword in the predicate table, raise an error if unknown.
*/
private Predicate resolvePredicate(StringView keyword) throws CodeSyntaxException {
Predicate predicate = predicateTable.get(keyword);
if (predicate == null) {
fail(error(PREDICATE_UNKNOWN).data(keyword.repr()));
// Emit a dummy predicate with this name.
return new BasePredicate(keyword.repr(), false) { };
}
return predicate;
}
/**
* After we've resolved a predicate implementation, parse its optional arguments.
*/
private Arguments parsePredicateArguments(Predicate predicate) throws CodeSyntaxException {
StringView rawArgs = null;
if (matcher.predicateArgs()) {
rawArgs = matcher.consume();
}
Arguments args = null;
if (rawArgs == null) {
args = new Arguments();
if (predicate.requiresArgs()) {
fail(error(PREDICATE_NEEDS_ARGS).data(predicate));
return null;
}
} else {
args = new Arguments(rawArgs);
}
try {
predicate.validateArgs(args);
} catch (ArgumentsException e) {
String identifier = predicate.identifier();
fail(error(PREDICATE_ARGS_INVALID).name(identifier).data(e.getMessage()));
return null;
}
return args;
}
/**
* Parse boolean expression inside an IF instruction.
*
* NOTE: This does not currently enforce one type of boolean operator in the expression, so you
* can mix OR with AND if you want, but there is no operator precedence or parenthesis so the
* result may not be what was expected.
*/
private boolean parseIfExpression() throws CodeSyntaxException {
if (!matcher.whitespace()) {
fail(error(WHITESPACE_EXPECTED).data(matcher.remainder()));
return emitInvalid();
}
matcher.consume();
// First, check if this is a predicate expression. If so, parse it.
if (matcher.predicate()) {
Predicate predicate = resolvePredicate(matcher.consume());
Arguments args = parsePredicateArguments(predicate);
if (args == null) {
return emitInvalid();
}
try {
emitInstruction(maker.ifpred(predicate, args));
} catch (ArgumentsException e) {
String identifier = predicate.identifier();
fail(error(PREDICATE_ARGS_INVALID).name(identifier).data(e.getMessage()));
}
return true;
}
// Otherwise, this is an expression involving variable tests and operators.
// If we find N variables, we'll need N-1 operators.
List vars = new ArrayList<>();
List ops = new ArrayList<>();
int count = 0;
while (matcher.variable()) {
vars.add(matcher.consume().repr());
if (matcher.whitespace()) {
matcher.consume();
}
if (count == IF_VARIABLE_LIMIT) {
fail(error(IF_TOO_MANY_VARS).limit(IF_VARIABLE_LIMIT));
return emitInvalid();
}
count++;
if (!matcher.operator()) {
break;
}
Operator op = matcher.consume().repr().equals("&&") ? Operator.LOGICAL_AND : Operator.LOGICAL_OR;
ops.add(op);
if (matcher.whitespace()) {
matcher.consume();
}
}
if (!matcher.finished()) {
fail(error(IF_EXPECTED_VAROP).data(matcher.remainder()));
return emitInvalid();
}
if (vars.size() == 0) {
fail(error(IF_EMPTY));
return emitInvalid();
}
if (vars.size() != (ops.size() + 1)) {
fail(error(IF_TOO_MANY_OPERATORS));
return emitInvalid();
}
emitInstruction(maker.ifexpn(vars, ops));
return true;
}
/**
* Parse a SECTION or REPEATED instruction:
*
* ".section" VARIABLE
* ".repeated section" VARIABLE
*
*/
private boolean parseSection(InstructionType type) throws CodeSyntaxException {
if (!matcher.whitespace()) {
fail(error(WHITESPACE_EXPECTED).data(matcher.remainder()));
return emitInvalid();
}
matcher.consume();
if (type == InstructionType.REPEATED) {
if (!matcher.wordSection()) {
fail(error(MISSING_SECTION_KEYWORD).data(matcher.remainder()));
return emitInvalid();
}
matcher.consume();
if (!matcher.whitespace()) {
fail(error(WHITESPACE_EXPECTED).data(matcher.remainder()));
return emitInvalid();
}
matcher.consume();
}
if (!matcher.variable()) {
fail(error(VARIABLE_EXPECTED).data(matcher.remainder()));
return emitInvalid();
}
StringView variable = matcher.consume();
if (!matcher.finished()) {
fail(error(EXTRA_CHARS).type(type).data(matcher.remainder()));
return emitInvalid();
}
if (type == InstructionType.REPEATED) {
emitInstruction(maker.repeated(variable.repr()));
} else {
emitInstruction(maker.section(variable.repr()));
}
return true;
}
/**
* Parses a variable reference that can consist of one or more variable names followed
* by an optional list of formatters. Formatters can be chained so the output of one
* formatter can be "piped" into the next.
*/
private boolean parseVariable() throws CodeSyntaxException {
int start = matcher.matchStart();
Variables vars = parseVariables();
if (vars == null) {
return false;
}
VariableInst instruction = maker.var(vars);
List formatters = parseFormatters(instruction, start);
if (formatters == null) {
emitInstruction(instruction);
} else if (!formatters.isEmpty()) {
instruction.setFormatters(formatters);
emitInstruction(instruction);
}
return true;
}
/**
* Parse one or more variable references. Returns null if an error occurred.
*/
private Variables parseVariables() throws CodeSyntaxException {
if (!matcher.variable()) {
return null;
}
StringView token = matcher.consume();
Variables vars = new Variables(token.repr());
while (matcher.variablesDelimiter()) {
matcher.consume();
if (matcher.finished()) {
return null;
}
if (matcher.pipe() || !matcher.variable()) {
return null;
}
vars.add(matcher.consume().repr());
}
boolean matchedPipe = matcher.peek(0, '|');
// If we see JavaScript boolean or operator, skip. This would fail anyway
// when we tried to parse the second '|' as a formatter name, so since
// we've already matched one pipe, sanity-check here.
if (matchedPipe && matcher.peek(1, '|')) {
return null;
}
return vars;
}
private List parseBindings() throws CodeSyntaxException {
List bindings = new ArrayList<>();
while (matcher.word()) {
StringView name = matcher.consume();
if (!matcher.equalsign()) {
break;
}
matcher.skip();
if (!matcher.variable()) {
break;
}
Object[] reference = GeneralUtils.splitVariable(matcher.consume().repr());
Binding binding = new Binding(name.repr(), reference);
bindings.add(binding);
if (!matcher.whitespace()) {
break;
}
matcher.skip();
}
return bindings.isEmpty() ? null : bindings;
}
/**
* Parse a formatter chain that may follow either a variable reference
* or bind instruction.
*
* Returns:
* null - no PIPE character was seen, so no formatters exist.
* - we saw a PIPE but encountered an error
* - we parsed a valid list of formatters.
*/
private List parseFormatters(Formattable formattable, int start) throws CodeSyntaxException {
List formatters = null;
while (matcher.pipe()) {
matcher.consume();
if (!matcher.formatter()) {
fail(error(FORMATTER_INVALID, matcher.pointer() - start, false).name(matcher.remainder()));
emitInvalid();
return Collections.emptyList();
}
StringView name = matcher.consume();
Formatter formatter = formatterTable.get(name);
if (formatter == null) {
fail(error(FORMATTER_UNKNOWN, matcher.matchStart() - start, false).name(name));
emitInvalid();
return Collections.emptyList();
}
StringView rawArgs = null;
if (matcher.arguments()) {
rawArgs = matcher.consume();
}
Arguments args = Constants.EMPTY_ARGUMENTS;
if (formatter.requiresArgs() && rawArgs == null) {
fail(error(FORMATTER_NEEDS_ARGS, matcher.matchStart() - start, false).data(formatter));
emitInvalid();
return Collections.emptyList();
} else {
args = new Arguments(rawArgs);
}
try {
formatter.validateArgs(args);
} catch (ArgumentsException e) {
String identifier = formatter.identifier();
fail(error(FORMATTER_ARGS_INVALID, matcher.matchStart() - start, false)
.name(identifier)
.data(e.getMessage()));
emitInvalid();
return Collections.emptyList();
}
if (formatters == null) {
formatters = new ArrayList<>(2);
}
formatters.add(new FormatterCall(formatter, args));
}
// If the initial matcher.pipe() fails to enter the loop, this indicates an
// unexpected character exists after the instruction.
if (!matcher.finished()) {
emitInvalid();
return Collections.emptyList();
}
// If we parsed all the way to the ending meta character, we can return
// a valid formatter list.
return formatters;
}
/**
* Initial state for the tokenizer machine, representing the outermost parse scope.
* This machine is pretty simple as it only needs to track an alternating sequence
* of text / instructions.
*/
private final State stateInitial = new State() {
@Override
public State transition() throws CodeSyntaxException {
while (true) {
char ch = getc(index);
switch (ch) {
case EOF_CHAR:
// Input is finished. See if we have any text left to flush.
if (save < length) {
emitText(save, length);
}
// A bit niche, but indicate the line number where the EOF occurred.
instLine = lineCounter;
instOffset = index - lineIndex;
emitInstruction(maker.eof());
return stateEOF;
case NEWLINE_CHAR:
// Keep track of which line we're currently on.
lineCounter++;
lineIndex = index + 1;
break;
case META_LEFT_CHAR:
instLine = lineCounter;
instOffset = index - lineIndex;
// Peek ahead to see if this is a multiline comment.
if ((getc(index + 1) == '#') && getc(index + 2) == '#') {
// Flush any text before the comment.
if (save < index) {
emitText(save, index);
}
index += 3;
return stateMultilineComment;
}
// Skip over duplicate META_LEFT characters until we find the last one
// before the corresponding META_RIGHT.
metaLeft = index;
break;
case META_RIGHT_CHAR:
// We found the right-hand boundary of a potential instruction.
if (metaLeft != -1) {
// Flush the text leading up to META_RIGHT, then attempt to parse the instruction.
if (save < metaLeft) {
emitText(save, metaLeft);
}
if (!matchMeta(metaLeft, index + 1)) {
// Nothing looked like a keyword or variable, so treat the sequence as plain text.
emitText(metaLeft, index + 1);
}
metaLeft = -1;
} else {
// Not an instruction candidate. Treat the entire sequence up to META_RIGHT as plain text.
emitText(save, index + 1);
}
// Set starting line of next instruction.
textLine = lineCounter;
textOffset = index + 1 - lineIndex;
save = index + 1;
break;
default:
break;
}
index++;
}
}
};
/**
* MULTILINE COMMENT state. {## ... ##}
*/
private final State stateMultilineComment = new State() {
@Override
public State transition() throws CodeSyntaxException {
int start = index;
while (true) {
char ch = getc(index);
switch (ch) {
case EOF_CHAR:
emitInstruction(maker.mcomment(raw, start, index));
fail(error(SyntaxErrorType.EOF_IN_COMMENT, true));
return stateEOF;
case NEWLINE_CHAR:
lineCounter++;
lineIndex = index + 1;
break;
case POUND_CHAR:
// Look-ahead for ##} sequence to terminate the comment block.
if (getc(index + 1) == POUND_CHAR && getc(index + 2) == META_RIGHT_CHAR) {
emitInstruction(maker.mcomment(raw, start, index), false);
// Skip over multi-line suffix.
index += 3;
save = index;
// Return to outer state.
return stateInitial;
}
break;
default:
break;
}
index++;
}
}
};
/**
* Terminal state when EOF on the input is reached.
*/
private final State stateEOF = new State() {
@Override
public State transition() throws CodeSyntaxException {
throw new RuntimeException("Tokenizer should never try to transition from the EOF state. "
+ "This is either a bug in the state machine or perhaps a tokenizer instance was reused.");
}
};
interface State {
State transition() throws CodeSyntaxException;
}
}
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