src/main/java/freemarker/core/_ErrorDescriptionBuilder.java - freemarker - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you 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 freemarker.core;

 import java.lang.reflect.Constructor;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;

 import freemarker.ext.beans._MethodUtil;
 import freemarker.log.Logger;
 import freemarker.template.Configuration;
 import freemarker.template.Template;
 import freemarker.template.utility.ClassUtil;
 import freemarker.template.utility.StringUtil;

 /**
  * Used internally only, might changes without notice!
  * Packs a structured from of the error description from which the error message can be rendered on-demand.
  * Note that this class isn't serializable, thus the containing exception should render the message before it's
  * serialized.
  */
 public class _ErrorDescriptionBuilder {

     private static final Logger LOG = Logger.getLogger("freemarker.runtime");

     private final String description;
     private final Object[] descriptionParts;
     private Expression blamed;
     private boolean showBlamer;
     private Object/*String|Object[]*/ tip;
     private Object[]/*String[]|Object[][]*/ tips;
     private Template template;

     public _ErrorDescriptionBuilder(String description) {
         this.description = description;
         this.descriptionParts = null;
     }

     /**
      * @param descriptionParts These will be concatenated to a single {@link String} in {@link #toString()}.
      *      {@link String} array items that look like FTL tag (must start with {@code "&lt;"} and end with {@code ">"})
      *      will be converted to the actual template syntax if {@link #blamed} or {@link #template} was set.
      */
     public _ErrorDescriptionBuilder(Object... descriptionParts) {
         this.descriptionParts = descriptionParts;
         this.description = null;
     }

     @Override
     public String toString() {
         return toString(null, true);
     }

     public String toString(TemplateElement parentElement, boolean showTips) {
         if (blamed == null && tips == null && tip == null && descriptionParts == null) return description;

         StringBuilder sb = new StringBuilder(200);

         if (parentElement != null && blamed != null && showBlamer) {
             try {
                 Blaming blaming = findBlaming(parentElement, blamed, 0);
                 if (blaming != null) {
                     sb.append("For ");
                     String nss = blaming.blamer.getNodeTypeSymbol();
                     char q = nss.indexOf('"') == -1 ? '\"' : '`';
                     sb.append(q).append(nss).append(q);
                     sb.append(" ").append(blaming.roleOfblamed).append(": ");
                 }
             } catch (Throwable e) {
                 // Should not happen. But we rather give a not-so-good error message than replace it with another...
                 // So we ignore this.
                 LOG.error("Error when searching blamer for better error message.", e);
             }
         }

         if (description != null) {
             sb.append(description);
         } else {
             appendParts(sb, descriptionParts);
         }

         String extraTip = null;
         if (blamed != null) {
             // Right-trim:
             for (int idx = sb.length() - 1; idx >= 0 && Character.isWhitespace(sb.charAt(idx)); idx --) {
                 sb.deleteCharAt(idx);
             }

             char lastChar = sb.length() > 0 ? (sb.charAt(sb.length() - 1)) : 0;
             if (lastChar != 0) {
                 sb.append('\n');
             }
             if (lastChar != ':') {
                 sb.append("The blamed expression:\n");
             }

             String[] lines = splitToLines(blamed.toString());
             for (int i = 0; i < lines.length; i++) {
                 sb.append(i == 0 ? "==> " : "\n    ");
                 sb.append(lines[i]);
             }

             sb.append("  [");
             sb.append(blamed.getStartLocation());
             sb.append(']');


             if (containsSingleInterpolatoinLiteral(blamed, 0)) {
                 extraTip = "It has been noticed that you are using ${...} as the sole content of a quoted string. That "
                         + "does nothing but forcably converts the value inside ${...} to string (as it inserts it into "
                         + "the enclosing string). "
                         + "If that's not what you meant, just remove the quotation marks, ${ and }; you don't need "
                         + "them. If you indeed wanted to convert to string, use myExpression?string instead.";
             }
         }

         if (showTips) {
             int allTipsLen = (tips != null ? tips.length : 0) + (tip != null ? 1 : 0) + (extraTip != null ? 1 : 0);
             Object[] allTips;
             if (tips != null && allTipsLen == tips.length) {
                 allTips = tips;
             } else {
                 allTips = new Object[allTipsLen];
                 int dst = 0;
                 if (tip != null) allTips[dst++] = tip;
                 if (tips != null) {
                     for (int i = 0; i < tips.length; i++) {
                         allTips[dst++] = tips[i];
                     }
                 }
                 if (extraTip != null) allTips[dst++] = extraTip;
             }
             if (allTips != null && allTips.length > 0) {
                 sb.append("\n\n");
                 for (int i = 0; i < allTips.length; i++) {
                     if (i != 0) sb.append('\n');
                     sb.append(_CoreAPI.ERROR_MESSAGE_HR).append('\n');
                     sb.append("Tip: ");
                     Object tip = allTips[i];
                     if (!(tip instanceof Object[])) {
                         sb.append(allTips[i]);
                     } else {
                         appendParts(sb, (Object[]) tip);
                     }
                 }
                 sb.append('\n').append(_CoreAPI.ERROR_MESSAGE_HR);
             }
         }

         return sb.toString();
     }

     private boolean containsSingleInterpolatoinLiteral(Expression exp, int recursionDepth) {
         if (exp == null) return false;

         // Just in case a loop ever gets into the AST somehow, try not fill the stack and such:
         if (recursionDepth > 20) return false;

         if (exp instanceof StringLiteral && ((StringLiteral) exp).isSingleInterpolationLiteral()) return true;

         int paramCnt = exp.getParameterCount();
         for (int i = 0; i < paramCnt; i++) {
             Object paramValue = exp.getParameterValue(i);
             if (paramValue instanceof Expression) {
                 boolean result = containsSingleInterpolatoinLiteral((Expression) paramValue, recursionDepth + 1);
                 if (result) return true;
             }
         }

         return false;
     }

     private Blaming findBlaming(TemplateObject parent, Expression blamed, int recursionDepth) {
         // Just in case a loop ever gets into the AST somehow, try not fill the stack and such:
         if (recursionDepth > 50) return null;

         int paramCnt = parent.getParameterCount();
         for (int i = 0; i < paramCnt; i++) {
             Object paramValue = parent.getParameterValue(i);
             if (paramValue == blamed) {
                 Blaming blaming = new Blaming();
                 blaming.blamer = parent;
                 blaming.roleOfblamed = parent.getParameterRole(i);
                 return blaming;
             } else if (paramValue instanceof TemplateObject) {
                 Blaming blaming = findBlaming((TemplateObject) paramValue, blamed, recursionDepth + 1);
                 if (blaming != null) return blaming;
             }
         }
         return null;
     }

     private void appendParts(StringBuilder sb, Object[] parts) {
         Template template = this.template != null ? this.template : (blamed != null ? blamed.getTemplate() : null);
         for (int i = 0; i < parts.length; i++) {
             Object partObj = parts[i];
             if (partObj instanceof Object[]) {
                 appendParts(sb, (Object[]) partObj);
             } else {
                 String partStr;
                 partStr = tryToString(partObj);
                 if (partStr == null) {
                     partStr = "null";
                 }

                 if (template != null) {
                     if (partStr.length() > 4
                             && partStr.charAt(0) == '<'
                             && (
                                     (partStr.charAt(1) == '#' || partStr.charAt(1) == '@')
                                     || (partStr.charAt(1) == '/') && (partStr.charAt(2) == '#' || partStr.charAt(2) == '@')
                                )
                             && partStr.charAt(partStr.length() - 1) == '>') {
                         if (template.getActualTagSyntax() == Configuration.SQUARE_BRACKET_TAG_SYNTAX) {
                             sb.append('[');
                             sb.append(partStr.substring(1, partStr.length() - 1));
                             sb.append(']');
                         } else {
                             sb.append(partStr);
                         }
                     } else {
                         sb.append(partStr);
                     }
                 } else {
                     sb.append(partStr);
                 }
             }
         }
     }

     /**
      * A twist on Java's toString that generates more appropriate results for generating error messages.
      */
     public static String toString(Object partObj) {
         return toString(partObj, false);
     }

     public static String tryToString(Object partObj) {
         return toString(partObj, true);
     }

     private static String toString(Object partObj, boolean suppressToStringException) {
         final String partStr;
         if (partObj == null) {
             return null;
         } else if (partObj instanceof Class) {
             partStr = ClassUtil.getShortClassName((Class) partObj);
         } else if (partObj instanceof Method || partObj instanceof Constructor) {
             partStr = _MethodUtil.toString((Member) partObj);
         } else {
             partStr = suppressToStringException ? StringUtil.tryToString(partObj) : partObj.toString();
         }
         return partStr;
     }

     private String[] splitToLines(String s) {
         s = StringUtil.replace(s, "\r\n", "\n");
         s = StringUtil.replace(s, "\r", "\n");
         String[] lines = StringUtil.split(s, '\n');
         return lines;
     }

     /**
      * Needed for description <em>parts</em> that look like an FTL tag to be converted, if there's no {@link #blamed}.
      */
     public _ErrorDescriptionBuilder template(Template template) {
         this.template = template;
         return this;
     }

     public _ErrorDescriptionBuilder blame(Expression blamedExpr) {
         this.blamed = blamedExpr;
         return this;
     }

     public _ErrorDescriptionBuilder showBlamer(boolean showBlamer) {
         this.showBlamer = showBlamer;
         return this;
     }

     public _ErrorDescriptionBuilder tip(String tip) {
         tip((Object) tip);
         return this;
     }

     public _ErrorDescriptionBuilder tip(Object... tip) {
         tip((Object) tip);
         return this;
     }

     private _ErrorDescriptionBuilder tip(Object tip) {
         if (this.tip == null) {
             this.tip = tip;
         } else {
             if (tips == null) {
                 tips = new Object[] { tip };
             } else {
                 final int origTipsLen = tips.length;

                 Object[] newTips = new Object[origTipsLen + 1];
                 for (int i = 0; i < origTipsLen; i++) {
                     newTips[i] = tips[i];
                 }
                 newTips[origTipsLen] = tip;
                 tips = newTips;
             }
         }
         return this;
     }

     public _ErrorDescriptionBuilder tips(Object... tips) {
         if (this.tips == null) {
             this.tips = tips;
         } else {
             final int origTipsLen = this.tips.length;
             final int additionalTipsLen = tips.length;

             Object[] newTips = new Object[origTipsLen + additionalTipsLen];
             for (int i = 0; i < origTipsLen; i++) {
                 newTips[i] = this.tips[i];
             }
             for (int i = 0; i < additionalTipsLen; i++) {
                 newTips[origTipsLen + i] = tips[i];
             }
             this.tips = newTips;
         }
         return this;
     }

     private static class Blaming {
         TemplateObject blamer;
         ParameterRole roleOfblamed;
     }

 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you 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 freemarker.core;

	import java.lang.reflect.Constructor;
	import java.lang.reflect.Member;
	import java.lang.reflect.Method;

	import freemarker.ext.beans._MethodUtil;
	import freemarker.log.Logger;
	import freemarker.template.Configuration;
	import freemarker.template.Template;
	import freemarker.template.utility.ClassUtil;
	import freemarker.template.utility.StringUtil;

	/**
	* Used internally only, might changes without notice!
	* Packs a structured from of the error description from which the error message can be rendered on-demand.
	* Note that this class isn't serializable, thus the containing exception should render the message before it's
	* serialized.
	*/
	public class _ErrorDescriptionBuilder {

	private static final Logger LOG = Logger.getLogger("freemarker.runtime");

	private final String description;
	private final Object[] descriptionParts;
	private Expression blamed;
	private boolean showBlamer;
	private Object/String\|Object[]/ tip;
	private Object[]/String[]\|Object[][]/ tips;
	private Template template;

	public _ErrorDescriptionBuilder(String description) {
	this.description = description;
	this.descriptionParts = null;
	}

	/**
	* @param descriptionParts These will be concatenated to a single {@link String} in {@link #toString()}.
	* {@link String} array items that look like FTL tag (must start with {@code "<"} and end with {@code ">"})
	* will be converted to the actual template syntax if {@link #blamed} or {@link #template} was set.
	*/
	public _ErrorDescriptionBuilder(Object... descriptionParts) {
	this.descriptionParts = descriptionParts;
	this.description = null;
	}

	@Override
	public String toString() {
	return toString(null, true);
	}

	public String toString(TemplateElement parentElement, boolean showTips) {
	if (blamed == null && tips == null && tip == null && descriptionParts == null) return description;

	StringBuilder sb = new StringBuilder(200);

	if (parentElement != null && blamed != null && showBlamer) {
	try {
	Blaming blaming = findBlaming(parentElement, blamed, 0);
	if (blaming != null) {
	sb.append("For ");
	String nss = blaming.blamer.getNodeTypeSymbol();
	char q = nss.indexOf('"') == -1 ? '\"' : '`';
	sb.append(q).append(nss).append(q);
	sb.append(" ").append(blaming.roleOfblamed).append(": ");
	}
	} catch (Throwable e) {
	// Should not happen. But we rather give a not-so-good error message than replace it with another...
	// So we ignore this.
	LOG.error("Error when searching blamer for better error message.", e);
	}
	}

	if (description != null) {
	sb.append(description);
	} else {
	appendParts(sb, descriptionParts);
	}

	String extraTip = null;
	if (blamed != null) {
	// Right-trim:
	for (int idx = sb.length() - 1; idx >= 0 && Character.isWhitespace(sb.charAt(idx)); idx --) {
	sb.deleteCharAt(idx);
	}

	char lastChar = sb.length() > 0 ? (sb.charAt(sb.length() - 1)) : 0;
	if (lastChar != 0) {
	sb.append('\n');
	}
	if (lastChar != ':') {
	sb.append("The blamed expression:\n");
	}

	String[] lines = splitToLines(blamed.toString());
	for (int i = 0; i < lines.length; i++) {
	sb.append(i == 0 ? "==> " : "\n ");
	sb.append(lines[i]);
	}

	sb.append(" [");
	sb.append(blamed.getStartLocation());
	sb.append(']');


	if (containsSingleInterpolatoinLiteral(blamed, 0)) {
	extraTip = "It has been noticed that you are using ${...} as the sole content of a quoted string. That "
	+ "does nothing but forcably converts the value inside ${...} to string (as it inserts it into "
	+ "the enclosing string). "
	+ "If that's not what you meant, just remove the quotation marks, ${ and }; you don't need "
	+ "them. If you indeed wanted to convert to string, use myExpression?string instead.";
	}
	}

	if (showTips) {
	int allTipsLen = (tips != null ? tips.length : 0) + (tip != null ? 1 : 0) + (extraTip != null ? 1 : 0);
	Object[] allTips;
	if (tips != null && allTipsLen == tips.length) {
	allTips = tips;
	} else {
	allTips = new Object[allTipsLen];
	int dst = 0;
	if (tip != null) allTips[dst++] = tip;
	if (tips != null) {
	for (int i = 0; i < tips.length; i++) {
	allTips[dst++] = tips[i];
	}
	}
	if (extraTip != null) allTips[dst++] = extraTip;
	}
	if (allTips != null && allTips.length > 0) {
	sb.append("\n\n");
	for (int i = 0; i < allTips.length; i++) {
	if (i != 0) sb.append('\n');
	sb.append(_CoreAPI.ERROR_MESSAGE_HR).append('\n');
	sb.append("Tip: ");
	Object tip = allTips[i];
	if (!(tip instanceof Object[])) {
	sb.append(allTips[i]);
	} else {
	appendParts(sb, (Object[]) tip);
	}
	}
	sb.append('\n').append(_CoreAPI.ERROR_MESSAGE_HR);
	}
	}

	return sb.toString();
	}

	private boolean containsSingleInterpolatoinLiteral(Expression exp, int recursionDepth) {
	if (exp == null) return false;

	// Just in case a loop ever gets into the AST somehow, try not fill the stack and such:
	if (recursionDepth > 20) return false;

	if (exp instanceof StringLiteral && ((StringLiteral) exp).isSingleInterpolationLiteral()) return true;

	int paramCnt = exp.getParameterCount();
	for (int i = 0; i < paramCnt; i++) {
	Object paramValue = exp.getParameterValue(i);
	if (paramValue instanceof Expression) {
	boolean result = containsSingleInterpolatoinLiteral((Expression) paramValue, recursionDepth + 1);
	if (result) return true;
	}
	}

	return false;
	}

	private Blaming findBlaming(TemplateObject parent, Expression blamed, int recursionDepth) {
	// Just in case a loop ever gets into the AST somehow, try not fill the stack and such:
	if (recursionDepth > 50) return null;

	int paramCnt = parent.getParameterCount();
	for (int i = 0; i < paramCnt; i++) {
	Object paramValue = parent.getParameterValue(i);
	if (paramValue == blamed) {
	Blaming blaming = new Blaming();
	blaming.blamer = parent;
	blaming.roleOfblamed = parent.getParameterRole(i);
	return blaming;
	} else if (paramValue instanceof TemplateObject) {
	Blaming blaming = findBlaming((TemplateObject) paramValue, blamed, recursionDepth + 1);
	if (blaming != null) return blaming;
	}
	}
	return null;
	}

	private void appendParts(StringBuilder sb, Object[] parts) {
	Template template = this.template != null ? this.template : (blamed != null ? blamed.getTemplate() : null);
	for (int i = 0; i < parts.length; i++) {
	Object partObj = parts[i];
	if (partObj instanceof Object[]) {
	appendParts(sb, (Object[]) partObj);
	} else {
	String partStr;
	partStr = tryToString(partObj);
	if (partStr == null) {
	partStr = "null";
	}

	if (template != null) {
	if (partStr.length() > 4
	&& partStr.charAt(0) == '<'
	&& (
	(partStr.charAt(1) == '#' \|\| partStr.charAt(1) == '@')
	\|\| (partStr.charAt(1) == '/') && (partStr.charAt(2) == '#' \|\| partStr.charAt(2) == '@')
	)
	&& partStr.charAt(partStr.length() - 1) == '>') {
	if (template.getActualTagSyntax() == Configuration.SQUARE_BRACKET_TAG_SYNTAX) {
	sb.append('[');
	sb.append(partStr.substring(1, partStr.length() - 1));
	sb.append(']');
	} else {
	sb.append(partStr);
	}
	} else {
	sb.append(partStr);
	}
	} else {
	sb.append(partStr);
	}
	}
	}
	}

	/**
	* A twist on Java's toString that generates more appropriate results for generating error messages.
	*/
	public static String toString(Object partObj) {
	return toString(partObj, false);
	}

	public static String tryToString(Object partObj) {
	return toString(partObj, true);
	}

	private static String toString(Object partObj, boolean suppressToStringException) {
	final String partStr;
	if (partObj == null) {
	return null;
	} else if (partObj instanceof Class) {
	partStr = ClassUtil.getShortClassName((Class) partObj);
	} else if (partObj instanceof Method \|\| partObj instanceof Constructor) {
	partStr = _MethodUtil.toString((Member) partObj);
	} else {
	partStr = suppressToStringException ? StringUtil.tryToString(partObj) : partObj.toString();
	}
	return partStr;
	}

	private String[] splitToLines(String s) {
	s = StringUtil.replace(s, "\r\n", "\n");
	s = StringUtil.replace(s, "\r", "\n");
	String[] lines = StringUtil.split(s, '\n');
	return lines;
	}

	/**
	* Needed for description <em>parts</em> that look like an FTL tag to be converted, if there's no {@link #blamed}.
	*/
	public _ErrorDescriptionBuilder template(Template template) {
	this.template = template;
	return this;
	}

	public _ErrorDescriptionBuilder blame(Expression blamedExpr) {
	this.blamed = blamedExpr;
	return this;
	}

	public _ErrorDescriptionBuilder showBlamer(boolean showBlamer) {
	this.showBlamer = showBlamer;
	return this;
	}

	public _ErrorDescriptionBuilder tip(String tip) {
	tip((Object) tip);
	return this;
	}

	public _ErrorDescriptionBuilder tip(Object... tip) {
	tip((Object) tip);
	return this;
	}

	private _ErrorDescriptionBuilder tip(Object tip) {
	if (this.tip == null) {
	this.tip = tip;
	} else {
	if (tips == null) {
	tips = new Object[] { tip };
	} else {
	final int origTipsLen = tips.length;

	Object[] newTips = new Object[origTipsLen + 1];
	for (int i = 0; i < origTipsLen; i++) {
	newTips[i] = tips[i];
	}
	newTips[origTipsLen] = tip;
	tips = newTips;
	}
	}
	return this;
	}

	public _ErrorDescriptionBuilder tips(Object... tips) {
	if (this.tips == null) {
	this.tips = tips;
	} else {
	final int origTipsLen = this.tips.length;
	final int additionalTipsLen = tips.length;

	Object[] newTips = new Object[origTipsLen + additionalTipsLen];
	for (int i = 0; i < origTipsLen; i++) {
	newTips[i] = this.tips[i];
	}
	for (int i = 0; i < additionalTipsLen; i++) {
	newTips[origTipsLen + i] = tips[i];
	}
	this.tips = newTips;
	}
	return this;
	}

	private static class Blaming {
	TemplateObject blamer;
	ParameterRole roleOfblamed;
	}

	}