All Downloads are FREE. Search and download functionalities are using the official Maven repository.
Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $
You can buy this project and download/modify it how often you want.
guru.nidi.graphviz.parse.Lexer Maven / Gradle / Ivy
/*
* Copyright © 2015 Stefan Niederhauser ([email protected] )
*
* 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 guru.nidi.graphviz.parse;
import java.io.*;
import java.util.HashMap;
import java.util.Map;
import static guru.nidi.graphviz.parse.Token.*;
class Lexer {
private static final Map KEYWORDS = new HashMap<>();
static {
KEYWORDS.put("strict", Token.STRICT);
KEYWORDS.put("graph", Token.GRAPH);
KEYWORDS.put("digraph", Token.DIGRAPH);
KEYWORDS.put("node", Token.NODE);
KEYWORDS.put("edge", Token.EDGE);
KEYWORDS.put("subgraph", Token.SUBGRAPH);
}
private static final char CH_EOF = (char) -1;
private final PushbackReader in;
private char ch;
Position pos;
public Lexer(Reader in, String name) throws IOException {
this.in = new PushbackReader(in);
pos = new Position(name);
readChar();
}
public Token token() throws IOException {
final Token sym = symbol();
if (sym != null) {
readChar();
return sym;
}
return numeralOrIdent();
}
private Token symbol() throws IOException {
switch (ch) {
case CH_EOF:
return new Token(EOF, ch);
case ';':
return new Token(SEMICOLON, ch);
case ',':
return new Token(COMMA, ch);
case '{':
return new Token(BRACE_OPEN, ch);
case '}':
return new Token(BRACE_CLOSE, ch);
case '=':
return new Token(EQUAL, ch);
case '[':
return new Token(BRACKET_OPEN, ch);
case ']':
return new Token(BRACKET_CLOSE, ch);
case ':':
return new Token(COLON, ch);
case '-':
final char next = readRawChar();
if (next == '-') {
return new Token(MINUS_MINUS, "--");
}
if (next == '>') {
return new Token(ARROW, "->");
}
unread('-', next);
return null;
default:
return null;
}
}
private Token numeralOrIdent() throws IOException {
if (ch == '-' || ch == '.' || (ch >= '0' && ch <= '9')) {
return numeral();
}
return ident();
}
private Token numeral() throws IOException {
final StringBuilder s = new StringBuilder();
do {
s.append(ch);
readRawChar();
} while (ch == '.' || (ch >= '0' && ch <= '9'));
sync();
return new Token(ID, SUB_NUMERAL, s.toString());
}
private Token ident() throws IOException {
if (ch == '"') {
return quotedIdent();
}
if (ch == '<') {
return htmlIdent();
}
if (isIdentStart()) {
return simpleIdent();
}
throw new ParserException(pos, "Found unexpected character '" + ch + "'");
}
private boolean isIdentStart() {
return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= 128 && ch <= 255) || ch == '_';
}
private Token quotedIdent() throws IOException {
final StringBuilder s = new StringBuilder();
readRawChar();
while (ch != '"' && ch != CH_EOF) {
s.append(ch);
readRawChar();
if (ch == '"' && s.charAt(s.length() - 1) == '\\') {
s.replace(s.length() - 1, s.length(), "\"");
readRawChar();
}
if (ch == '\n' && s.charAt(s.length() - 1) == '\\') {
s.delete(s.length() - 1, s.length());
readRawChar();
}
}
readChar();
return new Token(ID, SUB_QUOTED, s.toString());
}
private Token htmlIdent() throws IOException {
final StringBuilder s = new StringBuilder();
int level = 1;
readRawChar();
do {
s.append(ch);
readRawChar();
if (ch == '<') {
level++;
}
if (ch == '>') {
level--;
}
} while ((ch != '>' || level > 0) && ch != CH_EOF);
readChar();
return new Token(ID, SUB_HTML, s.toString());
}
private Token simpleIdent() throws IOException {
final StringBuilder s = new StringBuilder();
do {
s.append(ch);
readRawChar();
} while ((isIdentStart() || (ch >= '0' && ch <= '9')) && ch != CH_EOF);
sync();
final Integer key = KEYWORDS.get(s.toString().toLowerCase());
return key == null ? new Token(ID, SUB_SIMPLE, s.toString()) : new Token(key, s.toString());
}
private void sync() throws IOException {
if (ch <= ' ') {
readChar();
}
}
private char readChar() throws IOException {
do {
readRawChar();
if (ch == '/') {
readComment();
} else if (ch == '\n') {
pos.newLine();
final char next = readRawChar();
if (next == '#') {
do {
readRawChar();
} while (ch != '\n' && ch != CH_EOF);
} else {
unread('\n', next);
}
}
} while (ch <= ' ' && ch != CH_EOF);
return ch;
}
private void readComment() throws IOException {
final char next = readRawChar();
if (next == '/') {
do {
readRawChar();
} while (ch != '\n' && ch != CH_EOF);
} else if (next == '*') {
do {
do {
readRawChar();
} while (ch != '*' && ch != CH_EOF);
readRawChar();
} while (ch != '/' && ch != CH_EOF);
readRawChar();
} else {
unread('/', next);
}
}
private char readRawChar() throws IOException {
pos.newChar();
return ch = (char) in.read();
}
private void unread(char before, char next) throws IOException {
ch = before;
in.unread(next);
}
}
