Merge pull request #327 from jochenberger/speed-up-filter-compiler

avoid some costly calls to String#trim()

json-path/src/main/java/com/jayway/jsonpath/internal/CharacterIndex.java

@@ -17,14 +17,16 @@ public class CharacterIndex {
 
     private final CharSequence charSequence;
     private int position;
+    private int endPosition;
 
     public CharacterIndex(CharSequence charSequence) {
         this.charSequence = charSequence;
         this.position = 0;
+        this.endPosition = charSequence.length() - 1;
     }
 
     public int length() {
-        return charSequence.length();
+        return endPosition + 1;
     }
 
     public char charAt(int idx) {
@@ -39,6 +41,10 @@ public class CharacterIndex {
         return (charSequence.charAt(position) == c);
     }
 
+    public boolean lastCharIs(char c) {
+      return charSequence.charAt(endPosition) == c;
+    }
+
     public boolean nextCharIs(char c) {
         return inBounds(position + 1) && (charSequence.charAt(position + 1) == c);
     }
@@ -47,12 +53,21 @@ public class CharacterIndex {
         return setPosition(position + charCount);
     }
 
+    public int decrementEndPosition(int charCount) {
+        return setEndPosition(endPosition - charCount);
+    }
+
     public int setPosition(int newPosition) {
         //position = min(newPosition, charSequence.length() - 1);
         position = newPosition;
         return position;
     }
 
+    private int setEndPosition(int newPosition) {
+        endPosition = newPosition;
+        return endPosition;
+    }
+
     public int position(){
         return position;
     }
@@ -244,7 +259,7 @@ public class CharacterIndex {
     }
 
     public boolean currentIsTail() {
-        return position >= charSequence.length()-1;
+        return position >= endPosition;
     }
 
     public boolean hasMoreCharacters() {
@@ -252,7 +267,7 @@ public class CharacterIndex {
     }
 
     public boolean inBounds(int idx) {
-        return (idx >= 0) && (idx < charSequence.length());
+        return (idx >= 0) && (idx <= endPosition);
     }
     public boolean inBounds() {
         return inBounds(position);
@@ -281,9 +296,22 @@ public class CharacterIndex {
     }
 
     public CharacterIndex skipBlanks() {
-        while (inBounds() && currentChar() == SPACE){
+        while (inBounds() && position < endPosition  && currentChar() == SPACE){
             incrementPosition(1);
         }
         return this;
     }
+
+    private CharacterIndex skipBlanksAtEnd() {
+        while (inBounds() && position < endPosition && lastCharIs(SPACE)){
+            decrementEndPosition(1);
+        }
+        return this;
+    }
+
+    public CharacterIndex trim() {
+        skipBlanks();
+        skipBlanksAtEnd();
+        return this;
+    }
 }

json-path/src/main/java/com/jayway/jsonpath/internal/filter/FilterCompiler.java

@@ -54,20 +54,22 @@ public class FilterCompiler {
     }
 
     private FilterCompiler(String filterString) {
-        filterString = filterString.trim();
-        if (!filterString.startsWith("[") || !filterString.endsWith("]")) {
+        filter = new CharacterIndex(filterString);
+        filter.trim();
+        if (!filter.currentCharIs('[') || !filter.lastCharIs(']')) {
             throw new InvalidPathException("Filter must start with '[' and end with ']'. " + filterString);
         }
-        filterString = filterString.substring(1, filterString.length() - 1).trim();
-        if (!filterString.startsWith("?")) {
+        filter.incrementPosition(1);
+        filter.decrementEndPosition(1);
+        filter.trim();
+        if (!filter.currentCharIs('?')) {
             throw new InvalidPathException("Filter must start with '[?' and end with ']'. " + filterString);
         }
-        filterString = filterString.substring(1).trim();
-        if (!filterString.startsWith("(") || !filterString.endsWith(")")) {
+        filter.incrementPosition(1);
+        filter.trim();
+        if (!filter.currentCharIs('(') || !filter.lastCharIs(')')) {
             throw new InvalidPathException("Filter must start with '[?(' and end with ')]'. " + filterString);
         }
-
-        filter = new CharacterIndex(filterString);
     }
 
     public Predicate compile() {

json-path/src/main/java/com/jayway/jsonpath/internal/path/PathCompiler.java

@@ -45,9 +45,13 @@ public class PathCompiler {
     private final LinkedList<Predicate> filterStack;
     private final CharacterIndex path;
 
-    private PathCompiler(String path, LinkedList<Predicate> filterStack) {
+    private PathCompiler(String path, LinkedList<Predicate> filterStack){
+        this(new CharacterIndex(path), filterStack);
+    }
+
+    private PathCompiler(CharacterIndex path, LinkedList<Predicate> filterStack){
         this.filterStack = filterStack;
-        this.path = new CharacterIndex(path);
+        this.path = path;
     }
 
     private Path compile() {
@@ -57,16 +61,18 @@ public class PathCompiler {
 
     public static Path compile(String path, final Predicate... filters) {
         try {
-            path = path.trim();
+            CharacterIndex ci = new CharacterIndex(path);
+            ci.trim();
 
-            if(!(path.charAt(0) == DOC_CONTEXT)  && !(path.charAt(0) == EVAL_CONTEXT)){
-                path = "$." + path;
+            if(!( ci.charAt(0) == DOC_CONTEXT)  && !( ci.charAt(0) == EVAL_CONTEXT)){
+                ci = new CharacterIndex("$." + path);
+                ci.trim();
             }
-            if(path.endsWith(".")){
+            if(ci.lastCharIs('.')){
                 fail("Path must not end with a '.' or '..'");
             }
-            LinkedList filterStack = new LinkedList<Predicate>(asList(filters));
-            Path p = new PathCompiler(path.trim(), filterStack).compile();
+            LinkedList<Predicate> filterStack = new LinkedList<Predicate>(asList(filters));
+            Path p = new PathCompiler(ci, filterStack).compile();
             return p;
         } catch (Exception e) {
             InvalidPathException ipe;