add support for Liquid assign + Fix JSON unicode encoding and add character check in validator for illegal XML Unicode characters

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/LiquidEngine.java

@@ -47,6 +47,7 @@ import org.hl7.fhir.r5.model.ValueSet;
 import org.hl7.fhir.r5.utils.FHIRPathEngine.ExpressionNodeWithOffset;
 import org.hl7.fhir.r5.utils.FHIRPathEngine.IEvaluationContext;
 import org.hl7.fhir.utilities.Utilities;
+import org.hl7.fhir.utilities.i18n.I18nConstants;
 import org.hl7.fhir.utilities.xhtml.NodeType;
 import org.hl7.fhir.utilities.xhtml.XhtmlNode;
 
@@ -67,17 +68,27 @@ public class LiquidEngine implements IEvaluationContext {
 
   private class LiquidEngineContext {
     private Object externalContext;
-    private Map<String, Base> vars = new HashMap<>();
+    private Map<String, Base> loopVars = new HashMap<>();
+    private Map<String, Base> globalVars = new HashMap<>();
 
     public LiquidEngineContext(Object externalContext) {
       super();
       this.externalContext = externalContext;
+      globalVars = new HashMap<>();
+    }
+
+    public LiquidEngineContext(Object externalContext, LiquidEngineContext existing) {
+      super();
+      this.externalContext = externalContext;
+      loopVars.putAll(existing.loopVars);
+      globalVars = existing.globalVars;
     }
 
     public LiquidEngineContext(LiquidEngineContext existing) {
       super();
       externalContext = existing.externalContext;
-      vars.putAll(existing.vars);
+      loopVars.putAll(existing.loopVars);
+      globalVars = existing.globalVars;
     }
   }
 
@@ -185,7 +196,7 @@ public class LiquidEngine implements IEvaluationContext {
             String f = lexer.getCurrent();
             LiquidFilter filter = LiquidFilter.fromCode(f);
             if (filter == null) {
-              lexer.error("Unknown Liquid filter '"+f+"'");
+              lexer.error(engine.getWorker().formatMessage(I18nConstants.LIQUID_UNKNOWN_FILTER, f));
             }
             lexer.next();
             if (!lexer.done() && lexer.getCurrent().equals(":")) {
@@ -195,7 +206,7 @@ public class LiquidEngine implements IEvaluationContext {
               compiled.add(new LiquidExpressionNode(filter, null));
             }
           } else {
-            lexer.error("Unexpected syntax parsing liquid statement");
+            lexer.error(engine.getWorker().formatMessage(I18nConstants.LIQUID_UNKNOWN_SYNTAX)); 
           }
         }
       }
@@ -305,6 +316,30 @@ public class LiquidEngine implements IEvaluationContext {
     }
   }
 
+  private class LiquidAssign extends LiquidNode {
+    private String varName;
+    private String expression;
+    private ExpressionNode compiled;
+    @Override
+    public void evaluate(StringBuilder b, Base resource, LiquidEngineContext ctxt) throws FHIRException {
+      if (compiled == null) {
+        boolean dbl = engine.isAllowDoubleQuotes();
+        engine.setAllowDoubleQuotes(true);
+        ExpressionNodeWithOffset po = engine.parsePartial(expression, 0);
+        compiled = po.getNode();
+        engine.setAllowDoubleQuotes(dbl);
+      }
+      List<Base> list = engine.evaluate(ctxt, resource, resource, resource, compiled);
+      if (list.isEmpty()) {
+        ctxt.globalVars.remove(varName);
+      } else if (list.size() == 1) {
+        ctxt.globalVars.put(varName, list.get(0));
+      } else {
+        throw new Error("Assign returned a list?");
+      }      
+    }    
+  }
+  
   private class LiquidFor extends LiquidNode {
     private String varName;
     private String condition;
@@ -343,7 +378,10 @@ public class LiquidEngine implements IEvaluationContext {
           if (limit >= 0 && i == limit) {
             break;
           }          
-          lctxt.vars.put(varName, o);
+          if (lctxt.globalVars.containsKey(varName)) {
+            throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_VARIABLE_ALREADY_ASSIGNED, varName));
+          }
+          lctxt.loopVars.put(varName, o);
           boolean wantBreak = false;
           for (LiquidNode n : body) {
             try {
@@ -372,7 +410,7 @@ public class LiquidEngine implements IEvaluationContext {
         } else if (cnt.startsWith("limit")) {
           cnt = cnt.substring(5).trim();
           if (!cnt.startsWith(":")) {
-            throw new FHIRException("Exception evaluating "+src+": limit is not followed by ':'");
+            throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_COLON, src));
           }
           cnt = cnt.substring(1).trim();
           int i = 0;
@@ -380,14 +418,14 @@ public class LiquidEngine implements IEvaluationContext {
             i++;
           }
           if (i == 0) {
-            throw new FHIRException("Exception evaluating "+src+": limit is not followed by a number");
+            throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_NUMBER, src));
           }
           limit = Integer.parseInt(cnt.substring(0, i));
           cnt = cnt.substring(i);
         } else if (cnt.startsWith("offset")) {
           cnt = cnt.substring(6).trim();
           if (!cnt.startsWith(":")) {
-            throw new FHIRException("Exception evaluating "+src+": limit is not followed by ':'");
+            throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_COLON, src));
           }
           cnt = cnt.substring(1).trim();
           int i = 0;
@@ -395,12 +433,12 @@ public class LiquidEngine implements IEvaluationContext {
             i++;
           }
           if (i == 0) {
-            throw new FHIRException("Exception evaluating "+src+": limit is not followed by a number");
+            throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_NUMBER, src));
           }
           offset = Integer.parseInt(cnt.substring(0, i));
           cnt = cnt.substring(i);
         } else {
-          throw new FHIRException("Exception evaluating "+src+": unexpected content at "+cnt);
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_UNEXPECTED, cnt));
         }
       }      
     }
@@ -415,9 +453,9 @@ public class LiquidEngine implements IEvaluationContext {
       String src = includeResolver.fetchInclude(LiquidEngine.this, page);
       LiquidParser parser = new LiquidParser(src);
       LiquidDocument doc = parser.parse(page);
-      LiquidEngineContext nctxt = new LiquidEngineContext(ctxt.externalContext);
+      LiquidEngineContext nctxt = new LiquidEngineContext(ctxt.externalContext, ctxt);
       Tuple incl = new Tuple();
-      nctxt.vars.put("include", incl);
+      nctxt.loopVars.put("include", incl);
       for (String s : params.keySet()) {
         incl.addProperty(s, engine.evaluate(ctxt, resource, resource, resource, params.get(s)));
       }
@@ -474,11 +512,11 @@ public class LiquidEngine implements IEvaluationContext {
       cnt = "," + cnt.substring(5).trim();
       while (!Utilities.noString(cnt)) {
         if (!cnt.startsWith(",")) {
-          throw new FHIRException("Script " + name + ": Script " + name + ": Found " + cnt.charAt(0) + " expecting ',' parsing cycle");
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_EXPECTING, name, cnt.charAt(0), ','));
         }
         cnt = cnt.substring(1).trim();
         if (!cnt.startsWith("\"")) {
-          throw new FHIRException("Script " + name + ": Script " + name + ": Found " + cnt.charAt(0) + " expecting '\"' parsing cycle");
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_EXPECTING, name, cnt.charAt(0), '"'));
         }
         cnt = cnt.substring(1);
         int i = 0;
@@ -486,7 +524,7 @@ public class LiquidEngine implements IEvaluationContext {
           i++;
         }
         if (i == cnt.length()) {
-          throw new FHIRException("Script " + name + ": Script " + name + ": Found unterminated string parsing cycle");
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_UNTERMINATED, name));
         }
         res.list.add(cnt.substring(0, i));
         cnt = cnt.substring(i + 1).trim();
@@ -518,8 +556,10 @@ public class LiquidEngine implements IEvaluationContext {
               list.add(parseCycle(cnt));
             else if (cnt.startsWith("include "))
               list.add(parseInclude(cnt.substring(7).trim()));
+            else if (cnt.startsWith("assign "))
+              list.add(parseAssign(cnt.substring(6).trim()));
             else
-              throw new FHIRException("Script " + name + ": Script " + name + ": Unknown flow control statement " + cnt);
+              throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_UNKNOWN_FLOW_STMT,name, cnt));
           } else { // next2() == '{'
             list.add(parseStatement());
           }
@@ -533,7 +573,7 @@ public class LiquidEngine implements IEvaluationContext {
         n.closeUp();
       if (terminators.length > 0)
         if (!isTerminator(close, terminators))
-          throw new FHIRException("Script " + name + ": Script " + name + ": Found end of script looking for " + terminators);
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_UNKNOWN_NOEND, name, terminators));
       return close;
     }
 
@@ -577,7 +617,7 @@ public class LiquidEngine implements IEvaluationContext {
       while (i < cnt.length() && !Character.isWhitespace(cnt.charAt(i)))
         i++;
       if (i == cnt.length() || i == 0)
-        throw new FHIRException("Script " + name + ": Error reading include: " + cnt);
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_INCLUDE, name + ": Error reading include: " + cnt));
       LiquidInclude res = new LiquidInclude();
       res.page = cnt.substring(0, i);
       while (i < cnt.length() && Character.isWhitespace(cnt.charAt(i)))
@@ -587,10 +627,10 @@ public class LiquidEngine implements IEvaluationContext {
         while (i < cnt.length() && cnt.charAt(i) != '=')
           i++;
         if (i >= cnt.length() || j == i)
-          throw new FHIRException("Script " + name + ": Error reading include: " + cnt);
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_INCLUDE, name,  cnt));
         String n = cnt.substring(j, i);
         if (res.params.containsKey(n))
-          throw new FHIRException("Script " + name + ": Error reading include: " + cnt);
+          throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_INCLUDE, name,  cnt));
         i++;
         ExpressionNodeWithOffset t = engine.parsePartial(cnt, i);
         i = t.getOffset();
@@ -607,13 +647,16 @@ public class LiquidEngine implements IEvaluationContext {
         i++;
       LiquidFor res = new LiquidFor();
       res.varName = cnt.substring(0, i);
+      if ("include".equals(res.varName)) {
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_VARIABLE_ILLEGAL, res.varName));
+      }
       while (Character.isWhitespace(cnt.charAt(i)))
         i++;
       int j = i;
       while (!Character.isWhitespace(cnt.charAt(i)))
         i++;
       if (!"in".equals(cnt.substring(j, i)))
-        throw new FHIRException("Script " + name + ": Script " + name + ": Error reading loop: " + cnt);
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_LOOP, name, cnt));
       res.condition = cnt.substring(i).trim();
       parseList(res.body, false, new String[] { "endloop" });
       return res;
@@ -625,13 +668,16 @@ public class LiquidEngine implements IEvaluationContext {
         i++;
       LiquidFor res = new LiquidFor();
       res.varName = cnt.substring(0, i);
+      if ("include".equals(res.varName)) {
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_VARIABLE_ILLEGAL, res.varName));
+      }
       while (Character.isWhitespace(cnt.charAt(i)))
         i++;
       int j = i;
       while (!Character.isWhitespace(cnt.charAt(i)))
         i++;
       if (!"in".equals(cnt.substring(j, i)))
-        throw new FHIRException("Script " + name + ": Script " + name + ": Error reading loop: " + cnt);
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_LOOP, name, cnt));
       res.condition = cnt.substring(i).trim();
       String term = parseList(res.body, true, new String[] { "endfor", "else" });
       if ("else".equals(term)) {
@@ -640,6 +686,20 @@ public class LiquidEngine implements IEvaluationContext {
       return res;
     }
 
+    private LiquidNode parseAssign(String cnt) throws FHIRException {
+      int i = 0;
+      while (!Character.isWhitespace(cnt.charAt(i)))
+        i++;
+      LiquidAssign res = new LiquidAssign();
+      res.varName = cnt.substring(0, i);
+      while (Character.isWhitespace(cnt.charAt(i)))
+        i++;
+      int j = i;
+      while (!Character.isWhitespace(cnt.charAt(i)))
+        i++;
+      res.expression = cnt.substring(i).trim();
+      return res;
+    }
 
     private String parseTag(char ch) throws FHIRException {
       grab();
@@ -649,7 +709,7 @@ public class LiquidEngine implements IEvaluationContext {
         b.append(grab());
       }
       if (!(next1() == '%' && next2() == '}'))
-        throw new FHIRException("Script " + name + ": Unterminated Liquid statement {% " + b.toString());
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_NOTERM, name,  "{% " + b.toString()));
       grab();
       grab();
       return b.toString().trim();
@@ -663,7 +723,7 @@ public class LiquidEngine implements IEvaluationContext {
         b.append(grab());
       }
       if (!(next1() == '}' && next2() == '}'))
-        throw new FHIRException("Script " + name + ": Unterminated Liquid statement {{ " + b.toString());
+        throw new FHIRException(engine.getWorker().formatMessage(I18nConstants.LIQUID_SYNTAX_NOTERM, name,  "{{ " + b.toString()));
       grab();
       grab();
       LiquidStatement res = new LiquidStatement();
@@ -676,8 +736,10 @@ public class LiquidEngine implements IEvaluationContext {
   @Override
   public List<Base> resolveConstant(Object appContext, String name, boolean beforeContext) throws PathEngineException {
     LiquidEngineContext ctxt = (LiquidEngineContext) appContext;
-    if (ctxt.vars.containsKey(name))
+    if (ctxt.loopVars.containsKey(name))
-      return new ArrayList<Base>(Arrays.asList(ctxt.vars.get(name)));
+      return new ArrayList<Base>(Arrays.asList(ctxt.loopVars.get(name)));
+    if (ctxt.globalVars.containsKey(name))
+      return new ArrayList<Base>(Arrays.asList(ctxt.globalVars.get(name)));
     if (externalHostServices == null)
       return new ArrayList<Base>();
     return externalHostServices.resolveConstant(ctxt.externalContext, name, beforeContext);

org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/formats/UnicodeCharacterTests.java

@@ -0,0 +1,44 @@
+package org.hl7.fhir.r5.formats;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+import org.hl7.fhir.exceptions.FHIRFormatError;
+import org.hl7.fhir.r5.formats.IParser.OutputStyle;
+import org.hl7.fhir.r5.model.Parameters;
+import org.hl7.fhir.r5.test.utils.TestingUtilities;
+import org.hl7.fhir.utilities.Utilities;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class UnicodeCharacterTests {
+
+  @Test
+  public void testUnicodeXml() throws FHIRFormatError, IOException {
+    XmlParser xml = new XmlParser();
+    xml.setOutputStyle(OutputStyle.PRETTY);
+    Parameters p = (Parameters) xml.parse(TestingUtilities.loadTestResource("r5", "unicode-problem.xml"));
+    Assertions.assertEquals("invalid: \u0013, not invalid: \r", p.getParameterFirstRep().getValue().primitiveValue());
+    FileOutputStream o = new FileOutputStream(Utilities.path("[tmp]", "unicode-problem.xml"));
+    xml.compose(o, p);
+    o.close();
+    p = (Parameters) xml.parse(new FileInputStream(Utilities.path("[tmp]", "unicode-problem.xml")));
+    Assertions.assertEquals("invalid: \u0013, not invalid: \r", p.getParameterFirstRep().getValue().primitiveValue());
+  }
+  
+
+  @Test
+  public void testUnicodeJson() throws FHIRFormatError, IOException {
+    JsonParser json = new JsonParser();
+    json.setOutputStyle(OutputStyle.PRETTY);
+    Parameters p = (Parameters) json.parse(TestingUtilities.loadTestResource("r5", "unicode-problem.json"));
+    Assertions.assertEquals("invalid: \u0013, not invalid: \r", p.getParameterFirstRep().getValue().primitiveValue());
+    FileOutputStream o = new FileOutputStream(Utilities.path("[tmp]", "unicode-problem.json"));
+    json.compose(o, p);
+    o.close();
+    p = (Parameters) json.parse(new FileInputStream(Utilities.path("[tmp]", "unicode-problem.json")));
+    Assertions.assertEquals("invalid: \u0013, not invalid: \r", p.getParameterFirstRep().getValue().primitiveValue());
+  }
+  
+}

org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/Utilities.java

@@ -984,7 +984,7 @@ public class Utilities {
       else if (isWhitespace(c)) {
         b.append("\\u"+Utilities.padLeft(Integer.toHexString(c), '0', 4));
       } else if (((int) c) < 32)
-        b.append("\\u" + Utilities.padLeft(String.valueOf((int) c), '0', 4));
+        b.append("\\u" + Utilities.padLeft(Integer.toHexString(c), '0', 4));
       else
         b.append(c);
     }

org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java

@@ -926,6 +926,24 @@ public class I18nConstants {
   public static final String VALUESET_CONCEPT_DISPLAY_PRESENCE_MIXED = "VALUESET_CONCEPT_DISPLAY_PRESENCE_MIXED";
   public static final String VALUESET_CONCEPT_DISPLAY_SCT_TAG_MIXED = "VALUESET_CONCEPT_DISPLAY_SCT_TAG_MIXED";
   public static final String CS_SCT_IPS_NOT_IPS = "CS_SCT_IPS_NOT_IPS";
+  public static final String UNICODE_XML_BAD_CHARS = "UNICODE_XML_BAD_CHARS";
+  public static final String LIQUID_UNKNOWN_FILTER = "LIQUID_UNKNOWN_FILTER";
+  public static final String LIQUID_UNKNOWN_SYNTAX = "LIQUID_UNKNOWN_SYNTAX";
+  public static final String LIQUID_SYNTAX_EXPECTING = "LIQUID_SYNTAX_EXPECTING";
+  public static final String LIQUID_SYNTAX_UNTERMINATED = "LIQUID_SYNTAX_UNTERMINATED";
+  public static final String LIQUID_UNKNOWN_FLOW_STMT = "LIQUID_UNKNOWN_FLOW_STMT";
+  public static final String LIQUID_UNKNOWN_NOEND = "LIQUID_UNKNOWN_NOEND";
+  public static final String LIQUID_SYNTAX_INCLUDE = "LIQUID_SYNTAX_INCLUDE";
+  public static final String LIQUID_SYNTAX_LOOP = "LIQUID_SYNTAX_LOOP";
+  public static final String LIQUID_SYNTAX_NOTERM = "LIQUID_SYNTAX_NOTERM";
+  public static final String LIQUID_UNKNOWN_NOTERM = "LIQUID_UNKNOWN_NOTERM";
+  public static final String LIQUID_SYNTAX_COLON = "LIQUID_SYNTAX_COLON";
+  public static final String LIQUID_SYNTAX_NUMBER = "LIQUID_SYNTAX_NUMBER";
+  public static final String LIQUID_SYNTAX_UNEXPECTED = "LIQUID_SYNTAX_UNEXPECTED";
+  public static final String LIQUID_VARIABLE_ALREADY_ASSIGNED = "LIQUID_VARIABLE_ALREADY_ASSIGNED";
+  public static final String LIQUID_VARIABLE_ILLEGAL = "LIQUID_VARIABLE_ILLEGAL";
+
+
 
 }
 

org.hl7.fhir.utilities/src/main/resources/Messages.properties

@@ -981,3 +981,21 @@ SD_ED_TYPE_WRONG_TYPE_other = The element has a type {0} which is not in the typ
 VALUESET_CONCEPT_DISPLAY_PRESENCE_MIXED = This include has some concepts with displays and some without - check that this is what is intended
 VALUESET_CONCEPT_DISPLAY_SCT_TAG_MIXED = This SNOMED-CT based include has some concepts with semantic tags (FSN terms) and some without (preferred terms) - check that this is what is intended
 CS_SCT_IPS_NOT_IPS = The Snomed CT code {0} ({1}) is not a member of the IPS free set
+UNICODE_XML_BAD_CHARS_one = This content includes the character {1} (hex value). This character is illegal in the XML version of FHIR, and there is generally no valid use for such characters
+UNICODE_XML_BAD_CHARS_other = This content includes the characters {1} (hex values). These characters are illegal in the XML version of FHIR, and there is generally no valid use for such characters
+LIQUID_UNKNOWN_FILTER = Unknown Liquid filter '''{0}''
+LIQUID_UNKNOWN_SYNTAX = Unexpected syntax parsing liquid statement
+LIQUID_SYNTAX_EXPECTING = Script {0}: Found ''{1}'' expecting ''{2}'' parsing cycle
+LIQUID_SYNTAX_UNTERMINATED = Script {0}: Found unterminated string parsing cycle
+LIQUID_UNKNOWN_FLOW_STMT = Script {0}: Unknown flow control statement ''{1}''
+LIQUID_UNKNOWN_NOEND = Script {0}: Found end of script looking for {1}
+LIQUID_SYNTAX_INCLUDE, = Script {0}: Error reading include: {1}
+LIQUID_SYNTAX_LOOP = Script {0}: Error reading loop: {1}
+LIQUID_SYNTAX_NOTERM = Script {0}: Unterminated Liquid statement {1}
+LIQUID_UNKNOWN_NOTERM = Script {0}: Unterminated Liquid statement {1}
+LIQUID_SYNTAX_COLON = Exception evaluating {0}: limit is not followed by '':''
+LIQUID_SYNTAX_NUMBER = Exception evaluating {0}: limit is not followed by a number
+LIQUID_SYNTAX_UNEXPECTED = Exception evaluating {0}: unexpected content at {1}
+LIQUID_VARIABLE_ALREADY_ASSIGNED = "Liquid Exception: The variable ''{0}'' already has an assigned value
+LIQUID_VARIABLE_ILLEGAL = "Liquid Exception: The variable name ''{0}'' cannot be used
+  

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java

@@ -2379,6 +2379,14 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
           ok = false;
         }
       }
+      Set<String> badChars = new HashSet<>();
+      for (char ch : e.primitiveValue().toCharArray()) {
+        if (ch < 32 && !(ch == '\r' || ch == '\n' || ch == '\t')) {
+          // can't get to here with xml - the parser fails if you try
+          badChars.add(Integer.toHexString(ch));
+        }        
+      }
+      warningPlural(errors, "2023-07-26", IssueType.INVALID, e.line(), e.col(), path, badChars.isEmpty(), badChars.size(), I18nConstants.UNICODE_XML_BAD_CHARS, badChars.toString());      
     }
     String regex = context.getExtensionString(ToolingExtensions.EXT_REGEX);
     // there's a messy history here - this extension snhould only be on the element definition itself, but for historical reasons