dim.java

java中比较著名的js引擎当属mozilla开源的rhino

         * Information about the function.
         */
        private FunctionSource fsource;

        /**
         * Array of breakpoint state for each source line.
         */
        private boolean[] breakpoints;

        /**
         * Current line number.
         */
        private int lineNumber;

        /**
         * Creates a new StackFrame.
         */
        private StackFrame(Context cx, Dim dim, FunctionSource fsource) {
            this.dim = dim;
            this.contextData = ContextData.get(cx);
            this.fsource = fsource;
            this.breakpoints = fsource.sourceInfo().breakpoints;
            this.lineNumber = fsource.firstLine();
        }

        /**
         * Called when the stack frame is entered.
         */
        public void onEnter(Context cx, Scriptable scope,
                            Scriptable thisObj, Object[] args) {
            contextData.pushFrame(this);
            this.scope = scope;
            this.thisObj = thisObj;
            if (dim.breakOnEnter) {
                dim.handleBreakpointHit(this, cx);
            }
        }

        /**
         * Called when the current position has changed.
         */
        public void onLineChange(Context cx, int lineno) {
            this.lineNumber = lineno;

            if (!breakpoints[lineno] && !dim.breakFlag) {
                boolean lineBreak = contextData.breakNextLine;
                if (lineBreak && contextData.stopAtFrameDepth >= 0) {
                    lineBreak = (contextData.frameCount()
                                 <= contextData.stopAtFrameDepth);
                }
                if (!lineBreak) {
                    return;
                }
                contextData.stopAtFrameDepth = -1;
                contextData.breakNextLine = false;
            }

            dim.handleBreakpointHit(this, cx);
        }

        /**
         * Called when an exception has been thrown.
         */
        public void onExceptionThrown(Context cx, Throwable exception) {
            dim.handleExceptionThrown(cx, exception, this);
        }

        /**
         * Called when the stack frame has been left.
         */
        public void onExit(Context cx, boolean byThrow,
                           Object resultOrException) {
            if (dim.breakOnReturn && !byThrow) {
                dim.handleBreakpointHit(this, cx);
            }
            contextData.popFrame();
        }

        /**
         * Returns the SourceInfo object for the function.
         */
        public SourceInfo sourceInfo() {
            return fsource.sourceInfo();
        }

        /**
         * Returns the ContextData object for the Context.
         */
        public ContextData contextData() {
            return contextData;
        }

        /**
         * Returns the scope object for this frame.
         */
        public Object scope() {
            return scope;
        }

        /**
         * Returns the 'this' object for this frame.
         */
        public Object thisObj() {
            return thisObj;
        }

        /**
         * Returns the source URL.
         */
        public String getUrl() {
            return fsource.sourceInfo().url();
        }

        /**
         * Returns the current line number.
         */
        public int getLineNumber() {
            return lineNumber;
        }
    }

    /**
     * Class to store information about a function.
     */
    public static class FunctionSource {

        /**
         * Information about the source of the function.
         */
        private SourceInfo sourceInfo;

        /**
         * Line number of the first line of the function.
         */
        private int firstLine;

        /**
         * The function name.
         */
        private String name;

        /**
         * Creates a new FunctionSource.
         */
        private FunctionSource(SourceInfo sourceInfo, int firstLine,
                                 String name) {
            if (name == null) throw new IllegalArgumentException();
            this.sourceInfo = sourceInfo;
            this.firstLine = firstLine;
            this.name = name;
        }

        /**
         * Returns the SourceInfo object that describes the source of the
         * function.
         */
        public SourceInfo sourceInfo() {
            return sourceInfo;
        }

        /**
         * Returns the line number of the first line of the function.
         */
        public int firstLine() {
            return firstLine;
        }

        /**
         * Returns the name of the function.
         */
        public String name() {
            return name;
        }
    }

    /**
     * Class to store information about a script source.
     */
    public static class SourceInfo {

        /**
         * An empty array of booleans.
         */
        private static final boolean[] EMPTY_BOOLEAN_ARRAY = new boolean[0];

        /**
         * The script.
         */
        private String source;

        /**
         * The URL of the script.
         */
        private String url;

        /**
         * The line at which the script starts.
         */
        private int minLine;

        /**
         * Array indicating which lines can have breakpoints set.
         */
        private boolean[] breakableLines;
        
        /**
         * Array indicating whether a breakpoint is set on the line.
         */
        private boolean[] breakpoints;

        /**
         * Array of FunctionSource objects for the functions in the script.
         */
        private FunctionSource[] functionSources;

        /**
         * Creates a new SourceInfo object.
         */
        private SourceInfo(String source, DebuggableScript[] functions,
                             String normilizedUrl) {
            this.source = source;
            this.url = normilizedUrl;

            int N = functions.length;
            int[][] lineArrays = new int[N][];
            for (int i = 0; i != N; ++i) {
                lineArrays[i] = functions[i].getLineNumbers();
            }

            int minAll = 0, maxAll = -1;
            int[] firstLines = new int[N];
            for (int i = 0; i != N; ++i) {
                int[] lines = lineArrays[i];
                if (lines == null || lines.length == 0) {
                    firstLines[i] = -1;
                } else {
                    int min, max;
                    min = max = lines[0];
                    for (int j = 1; j != lines.length; ++j) {
                        int line = lines[j];
                        if (line < min) {
                            min = line;
                        } else if (line > max) {
                            max = line;
                        }
                    }
                    firstLines[i] = min;
                    if (minAll > maxAll) {
                        minAll = min;
                        maxAll = max;
                    } else {
                        if (min < minAll) {
                            minAll = min;
                        }
                        if (max > maxAll) {
                            maxAll = max;
                        }
                    }
                }
            }

            if (minAll > maxAll) {
                // No line information
                this.minLine = -1;
                this.breakableLines = EMPTY_BOOLEAN_ARRAY;
                this.breakpoints = EMPTY_BOOLEAN_ARRAY;
            } else {
                if (minAll < 0) {
                    // Line numbers can not be negative
                    throw new IllegalStateException(String.valueOf(minAll));
                }
                this.minLine = minAll;
                int linesTop = maxAll + 1;
                this.breakableLines = new boolean[linesTop];
                this.breakpoints = new boolean[linesTop];
                for (int i = 0; i != N; ++i) {
                    int[] lines = lineArrays[i];
                    if (lines != null && lines.length != 0) {
                        for (int j = 0; j != lines.length; ++j) {
                            int line = lines[j];
                            this.breakableLines[line] = true;
                        }
                    }
                }
            }
            this.functionSources = new FunctionSource[N];
            for (int i = 0; i != N; ++i) {
                String name = functions[i].getFunctionName();
                if (name == null) {
                    name = "";
                }
                this.functionSources[i]
                    = new FunctionSource(this, firstLines[i], name);
            }
        }

        /**
         * Returns the source text.
         */
        public String source() {
            return this.source;
        }

        /**
         * Returns the script's origin URL.
         */
        public String url() {
            return this.url;
        }

        /**
         * Returns the number of FunctionSource objects stored in this object.
         */
        public int functionSourcesTop() {
            return functionSources.length;
        }

        /**
         * Returns the FunctionSource object with the given index.
         */
        public FunctionSource functionSource(int i) {
            return functionSources[i];
        }

        /**
         * Copies the breakpoints from the given SourceInfo object into this
         * one.
         */
        private void copyBreakpointsFrom(SourceInfo old) {
            int end = old.breakpoints.length;
            if (end > this.breakpoints.length) {
                end = this.breakpoints.length;
            }
            for (int line = 0; line != end; ++line) {
                if (old.breakpoints[line]) {
                    this.breakpoints[line] = true;
                }
            }
        }

        /**
         * Returns whether the given line number can have a breakpoint set on
         * it.
         */
        public boolean breakableLine(int line) {
            return (line < this.breakableLines.length)
                   && this.breakableLines[line];
        }

        /**
         * Returns whether there is a breakpoint set on the given line.
         */
        public boolean breakpoint(int line) {
            if (!breakableLine(line)) {
                throw new IllegalArgumentException(String.valueOf(line));
            }
            return line < this.breakpoints.length && this.breakpoints[line];
        }

        /**
         * Sets or clears the breakpoint flag for the given line.
         */
        public boolean breakpoint(int line, boolean value) {
            if (!breakableLine(line)) {
                throw new IllegalArgumentException(String.valueOf(line));
            }
            boolean changed;
            synchronized (breakpoints) {
                if (breakpoints[line] != value) {
                    breakpoints[line] = value;
                    changed = true;
                } else {
                    changed = false;
                }
            }
            return changed;
        }

        /**
         * Removes all breakpoints from the script.
         */
        public void removeAllBreakpoints() {
            synchronized (breakpoints) {
                for (int line = 0; line != breakpoints.length; ++line) {
                    breakpoints[line] = false;
                }
            }
        }
    }
}