org.snapscript.parse.SourceCompressor Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of snap Show documentation
Show all versions of snap Show documentation
Dynamic scripting for the JVM
package org.snapscript.parse;
import static org.snapscript.parse.TextCategory.INDEX;
public class SourceCompressor {
private static final int LINE_LIMIT = 32000;
private char[] original;
private char[] compress;
private short[] lines;
private short line;
private char space;
private int write;
private int read;
private int count;
public SourceCompressor(char[] original) {
this.lines = new short[original.length];
this.compress = new char[original.length];
this.count = original.length;
this.original = original;
this.space = ' ';
this.line = 1; // lines start at 1
}
public SourceCode compress() {
if(read < count) {
directive(); // read interpreter directive
}
while(read < count) {
char next = original[read];
if(comment(next)) {
if(!comment()) {
lines[write] = line;
compress[write++] = original[read++];
}
} else if(quote(next)) {
if(!string()) {
lines[write] = line;
compress[write++] = original[read++];
}
} else if(!space(next)) {
lines[write] = line;
compress[write++] = original[read++];
space = ' ';
} else {
if(write > 0 && read +1 < count) { // some read and not finished
char before = compress[write-1];
char after = original[read+1];
if(identifier(before) && identifier(after)) {
lines[write] = line;
compress[write++] = space;
} else if(operator(before) && operator(after)) {
lines[write] = line;
compress[write++] = space;
}
}
if(next == '\n') {
if(line > LINE_LIMIT) {
throw new SourceException("Source exceeds " + LINE_LIMIT + " lines");
}
space = '\n'; // replace next with line feed
line++;
} else if(next == '\r') {
space = '\n'; // replace carriage return
}
read++;
}
}
return create();
}
private SourceCode create() {
char[] text = new char[write];
short[] index = new short[write];
short[] types = new short[write];
if(write == 0) {
throw new SourceException("Source text is empty");
}
for(int i = 0; i < write; i++) {
char next = compress[i];
if(next < INDEX.length) {
types[i] = INDEX[next];
}
index[i] = lines[i];
text[i] = next;
}
return new SourceCode(original, text, index, types, line);
}
private boolean directive() {
char start = original[read];
if(directive(start)){
if(read + 1 < count) {
char next = original[read + 1];
if(next == '!') {
while(read < count) {
char terminal = original[read];
if(terminal == '\n') {
if(line > LINE_LIMIT) {
throw new SourceException("Source exceeds " + LINE_LIMIT + " lines");
}
read++;
line++;
return true;
}
read++;
}
return true; // end of source
}
}
}
return false;
}
private boolean comment() {
char start = original[read];
if(comment(start)){
if(read + 1 < count) {
char next = original[read + 1];
if(next == '/') {
while(read < count) {
char terminal = original[read];
if(terminal == '\n') {
if(line > LINE_LIMIT) {
throw new SourceException("Source exceeds " + LINE_LIMIT + " lines");
}
read++;
line++;
return true;
}
read++;
}
return true; // end of source
}
if(next == '*') {
while(read < count) {
char terminal = original[read];
if(terminal == '\n') {
if(line > LINE_LIMIT) {
throw new SourceException("Source exceeds " + LINE_LIMIT + " lines");
}
line++;
}
if(terminal == '/' && read > 0) {
char prev = original[read - 1];
if(prev == '*') {
read++;
return true;
}
}
read++;
}
throw new SourceException("Comment not closed at line " + line);
}
}
}
return false;
}
private boolean string() {
char start = original[read];
if(quote(start)) {
int size = 0;
while(read < count) {
char next = original[read];
if(next == start) {
if(size == 1) { // "" or ''
lines[write] = line;
compress[write++] = original[read++];
return true;
}
if(read > 0 && size > 0) {
char prev = original[read - 1];
if(!escape(prev)) {
lines[write] = line;
compress[write++] = original[read++];
return true;
}
for(int i = 1; i <= size; i++) {
char value = original[read - i];
if(!escape(value)) {
if(i % 2 == 1) {
lines[write] = line;
compress[write++] = original[read++];
return true;
}
break;
}
}
}
}
if(next == '\n') {
if(line > LINE_LIMIT) {
throw new SourceException("Source exceeds " + LINE_LIMIT + " lines");
}
line++;
}
lines[write] = line;
compress[write++] = original[read++];
size++;
}
throw new SourceException("String literal not closed at line " + line);
}
return false;
}
private boolean escape(char value) {
return value == '\\';
}
private boolean directive(char value) {
return value == '#';
}
private boolean comment(char value) {
return value == '/';
}
private boolean quote(char value) {
switch(value){
case '"': case '\'':
case '`':
return true;
default:
return false;
}
}
private boolean space(char value) {
switch(value){
case ' ': case '\t':
case '\n': case '\r':
return true;
default:
return false;
}
}
private boolean identifier(char value) {
if(value >= 'a' && value <= 'z') {
return true;
}
if(value >= 'A' && value <= 'Z') {
return true;
}
if(value >= '0' && value <= '9') {
return true;
}
return false;
}
private boolean operator(char value) {
switch(value) {
case '+': case '-':
case '/': case '*':
case '%':
return true;
}
return false;
}
}