org.mozilla.javascript.tools.idswitch.SwitchGenerator Maven / Gradle / Ivy
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Rhino is an open-source implementation of JavaScript written entirely in
Java. It is typically embedded into Java applications to provide
scripting to end users.
The newest version!
/* -*- Mode: java; tab-width: 4; indent-tabs-mode: 1; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript.tools.idswitch;
import org.mozilla.javascript.EvaluatorException;
import org.mozilla.javascript.tools.ToolErrorReporter;
public class SwitchGenerator {
String v_switch_label = "L0";
String v_label = "L";
String v_s = "s";
String v_c = "c";
String v_guess = "X";
String v_id = "id";
String v_length_suffix = "_length";
int use_if_threshold = 3;
int char_tail_test_threshold = 2;
private IdValuePair[] pairs;
private String default_value;
private int[] columns;
private boolean c_was_defined;
private CodePrinter P;
private ToolErrorReporter R;
private String source_file;
public CodePrinter getCodePrinter() { return P; }
public void setCodePrinter(CodePrinter value) { P = value; }
public ToolErrorReporter getReporter() { return R; }
public void setReporter(ToolErrorReporter value) { R = value; }
public String getSourceFileName() { return source_file; }
public void setSourceFileName(String value) { source_file = value; }
public void generateSwitch(String[] pairs, String default_value) {
int N = pairs.length / 2;
IdValuePair[] id_pairs = new IdValuePair[N];
for (int i = 0; i != N; ++i) {
id_pairs[i] = new IdValuePair(pairs[2 * i], pairs[2 * i + 1]);
}
generateSwitch(id_pairs, default_value);
}
public void generateSwitch(IdValuePair[] pairs, String default_value) {
int begin = 0;
int end = pairs.length;
if (begin == end) { return; }
this.pairs = pairs;
this.default_value = default_value;
generate_body(begin, end, 2);
}
private void generate_body(int begin, int end, int indent_level) {
P.indent(indent_level);
P.p(v_switch_label); P.p(": { ");
P.p(v_id); P.p(" = "); P.p(default_value);
P.p("; String "); P.p(v_guess); P.p(" = null;");
c_was_defined = false;
int c_def_begin = P.getOffset();
P.p(" int "); P.p(v_c); P.p(';');
int c_def_end = P.getOffset();
P.nl();
generate_length_switch(begin, end, indent_level + 1);
if (!c_was_defined) {
P.erase(c_def_begin, c_def_end);
}
P.indent(indent_level + 1);
P.p("if ("); P.p(v_guess); P.p("!=null && ");
P.p(v_guess); P.p("!="); P.p(v_s);
P.p(" && !"); P.p(v_guess); P.p(".equals("); P.p(v_s); P.p(")) ");
P.p(v_id); P.p(" = "); P.p(default_value); P.p(";"); P.nl();
// Add break at end of block to suppress warning for unused label
P.indent(indent_level + 1);
P.p("break "); P.p(v_switch_label); P.p(";"); P.nl();
P.line(indent_level, "}");
}
private void generate_length_switch(int begin, int end, int indent_level) {
sort_pairs(begin, end, -1);
check_all_is_different(begin, end);
int lengths_count = count_different_lengths(begin, end);
columns = new int[pairs[end - 1].idLength];
boolean use_if;
if (lengths_count <= use_if_threshold) {
use_if = true;
if (lengths_count != 1) {
P.indent(indent_level);
P.p("int "); P.p(v_s); P.p(v_length_suffix);
P.p(" = "); P.p(v_s); P.p(".length();");
P.nl();
}
}
else {
use_if = false;
P.indent(indent_level);
P.p(v_label); P.p(": switch (");
P.p(v_s); P.p(".length()) {");
P.nl();
}
int same_length_begin = begin;
int cur_l = pairs[begin].idLength, l = 0;
for (int i = begin;;) {
++i;
if (i == end || (l = pairs[i].idLength) != cur_l) {
int next_indent;
if (use_if) {
P.indent(indent_level);
if (same_length_begin != begin) { P.p("else "); }
P.p("if (");
if (lengths_count == 1) {
P.p(v_s); P.p(".length()==");
}
else {
P.p(v_s); P.p(v_length_suffix); P.p("==");
}
P.p(cur_l);
P.p(") {");
next_indent = indent_level + 1;
}
else {
P.indent(indent_level);
P.p("case "); P.p(cur_l); P.p(":");
next_indent = indent_level + 1;
}
generate_letter_switch
(same_length_begin, i, next_indent, !use_if, use_if);
if (use_if) {
P.p("}"); P.nl();
}
else {
P.p("break "); P.p(v_label); P.p(";"); P.nl();
}
if (i == end) { break; }
same_length_begin = i;
cur_l = l;
}
}
if (!use_if) {
P.indent(indent_level); P.p("}"); P.nl();
}
}
private void generate_letter_switch
(int begin, int end,
int indent_level, boolean label_was_defined, boolean inside_if)
{
int L = pairs[begin].idLength;
for (int i = 0; i != L; ++i) {
columns[i] = i;
}
generate_letter_switch_r
(begin, end, L, indent_level, label_was_defined, inside_if);
}
private boolean generate_letter_switch_r
(int begin, int end, int L,
int indent_level, boolean label_was_defined, boolean inside_if)
{
boolean next_is_unreachable = false;
if (begin + 1 == end) {
P.p(' ');
IdValuePair pair = pairs[begin];
if (L > char_tail_test_threshold) {
P.p(v_guess); P.p("="); P.qstring(pair.id); P.p(";");
P.p(v_id); P.p("="); P.p(pair.value); P.p(";");
}
else {
if (L == 0) {
next_is_unreachable = true;
P.p(v_id); P.p("="); P.p(pair.value);
P.p("; break "); P.p(v_switch_label); P.p(";");
}
else {
P.p("if (");
int column = columns[0];
P.p(v_s); P.p(".charAt("); P.p(column); P.p(")==");
P.qchar(pair.id.charAt(column));
for (int i = 1; i != L; ++i) {
P.p(" && ");
column = columns[i];
P.p(v_s); P.p(".charAt("); P.p(column); P.p(")==");
P.qchar(pair.id.charAt(column));
}
P.p(") {");
P.p(v_id); P.p("="); P.p(pair.value);
P.p("; break "); P.p(v_switch_label); P.p(";}");
}
}
P.p(' ');
return next_is_unreachable;
}
int max_column_index = find_max_different_column(begin, end, L);
int max_column = columns[max_column_index];
int count = count_different_chars(begin, end, max_column);
columns[max_column_index] = columns[L - 1];
if (inside_if) { P.nl(); P.indent(indent_level); }
else { P.p(' '); }
boolean use_if;
if (count <= use_if_threshold) {
use_if = true;
c_was_defined = true;
P.p(v_c); P.p("="); P.p(v_s);
P.p(".charAt("); P.p(max_column); P.p(");");
}
else {
use_if = false;
if (!label_was_defined) {
label_was_defined = true;
P.p(v_label); P.p(": ");
}
P.p("switch ("); P.p(v_s);
P.p(".charAt("); P.p(max_column); P.p(")) {");
}
int same_char_begin = begin;
int cur_ch = pairs[begin].id.charAt(max_column), ch = 0;
for (int i = begin;;) {
++i;
if (i == end || (ch = pairs[i].id.charAt(max_column)) != cur_ch) {
int next_indent;
if (use_if) {
P.nl(); P.indent(indent_level);
if (same_char_begin != begin) { P.p("else "); }
P.p("if ("); P.p(v_c); P.p("==");
P.qchar(cur_ch); P.p(") {");
next_indent = indent_level + 1;
}
else {
P.nl(); P.indent(indent_level);
P.p("case "); P.qchar(cur_ch); P.p(":");
next_indent = indent_level + 1;
}
boolean after_unreachable = generate_letter_switch_r
(same_char_begin, i, L - 1,
next_indent, label_was_defined, use_if);
if (use_if) {
P.p("}");
}
else {
if (!after_unreachable) {
P.p("break "); P.p(v_label); P.p(";");
}
}
if (i == end) { break; }
same_char_begin = i;
cur_ch = ch;
}
}
if (use_if) {
P.nl();
if (inside_if) { P.indent(indent_level - 1); }
else { P.indent(indent_level); }
}
else {
P.nl(); P.indent(indent_level); P.p("}");
if (inside_if) { P.nl(); P.indent(indent_level - 1);}
else { P.p(' '); }
}
columns[max_column_index] = max_column;
return next_is_unreachable;
}
private int count_different_lengths(int begin, int end) {
int lengths_count = 0;
int cur_l = -1;
for (; begin != end; ++begin) {
int l = pairs[begin].idLength;
if (cur_l != l) {
++lengths_count; cur_l = l;
}
}
return lengths_count;
}
private int find_max_different_column(int begin, int end, int L) {
int max_count = 0;
int max_index = 0;
for (int i = 0; i != L; ++i) {
int column = columns[i];
sort_pairs(begin, end, column);
int count = count_different_chars(begin, end, column);
if (count == end - begin) { return i; }
if (max_count < count) {
max_count = count;
max_index = i;
}
}
if (max_index != L - 1) {
sort_pairs(begin, end, columns[max_index]);
}
return max_index;
}
private int count_different_chars(int begin, int end, int column) {
int chars_count = 0;
int cur_ch = -1;
for (; begin != end; ++begin) {
int ch = pairs[begin].id.charAt(column);
if (ch != cur_ch) {
++chars_count; cur_ch = ch;
}
}
return chars_count;
}
private void check_all_is_different(int begin, int end) {
if (begin != end) {
IdValuePair prev = pairs[begin];
while (++begin != end) {
IdValuePair current = pairs[begin];
if (prev.id.equals(current.id)) {
throw on_same_pair_fail(prev, current);
}
prev = current;
}
}
}
private EvaluatorException on_same_pair_fail(IdValuePair a, IdValuePair b) {
int line1 = a.getLineNumber(), line2 = b.getLineNumber();
if (line2 > line1) { int tmp = line1; line1 = line2; line2 = tmp; }
String error_text = ToolErrorReporter.getMessage(
"msg.idswitch.same_string", a.id, new Integer(line2));
return R.runtimeError(error_text, source_file, line1, null, 0);
}
private void sort_pairs(int begin, int end, int comparator) {
heap4Sort(pairs, begin, end - begin, comparator);
}
private static boolean bigger
(IdValuePair a, IdValuePair b, int comparator)
{
if (comparator < 0) {
// For length selection switch it is enough to compare just length,
// but to detect same strings full comparison is essential
//return a.idLength > b.idLength;
int diff = a.idLength - b.idLength;
if (diff != 0) { return diff > 0; }
return a.id.compareTo(b.id) > 0;
}
else {
return a.id.charAt(comparator) > b.id.charAt(comparator);
}
}
private static void heap4Sort
(IdValuePair[] array, int offset, int size, int comparator)
{
if (size <= 1) { return; }
makeHeap4(array, offset, size, comparator);
while (size > 1) {
--size;
IdValuePair v1 = array[offset + size];
IdValuePair v2 = array[offset + 0];
array[offset + size] = v2;
array[offset + 0] = v1;
heapify4(array, offset, size, 0, comparator);
}
}
private static void makeHeap4
(IdValuePair[] array, int offset, int size, int comparator)
{
for (int i = ((size + 2) >> 2); i != 0;) {
--i;
heapify4(array, offset, size, i, comparator);
}
}
private static void heapify4
(IdValuePair[] array, int offset, int size, int i, int comparator)
{
int new_i1, new_i2, new_i3;
IdValuePair i_val = array[offset + i];
for (;;) {
int base = (i << 2);
new_i1 = base | 1;
new_i2 = base | 2;
new_i3 = base | 3;
int new_i4 = base + 4;
if (new_i4 >= size) { break; }
IdValuePair val1 = array[offset + new_i1];
IdValuePair val2 = array[offset + new_i2];
IdValuePair val3 = array[offset + new_i3];
IdValuePair val4 = array[offset + new_i4];
if (bigger(val2, val1, comparator)) {
val1 = val2; new_i1 = new_i2;
}
if (bigger(val4, val3, comparator)) {
val3 = val4; new_i3 = new_i4;
}
if (bigger(val3, val1, comparator)) {
val1 = val3; new_i1 = new_i3;
}
if (bigger(i_val, val1, comparator)) { return; }
array[offset + i] = val1;
array[offset + new_i1] = i_val;
i = new_i1;
}
if (new_i1 < size) {
IdValuePair val1 = array[offset + new_i1];
if (new_i2 != size) {
IdValuePair val2 = array[offset + new_i2];
if (bigger(val2, val1, comparator)) {
val1 = val2; new_i1 = new_i2;
}
if (new_i3 != size) {
IdValuePair val3 = array[offset + new_i3];
if (bigger(val3, val1, comparator)) {
val1 = val3; new_i1 = new_i3;
}
}
}
if (bigger(val1, i_val, comparator)) {
array[offset + i] = val1;
array[offset + new_i1] = i_val;
}
}
}
}