split out function groups; implement numeric functions

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/branches/exprs@1117 f203690c-595d-4dc9-a70b-905162fa7fd2

src/main/java/com/healthmarketscience/jackcess/expr/EvalContext.java

@@ -17,6 +17,7 @@ limitations under the License.
 package com.healthmarketscience.jackcess.expr;
 
 import java.text.SimpleDateFormat;
+import java.util.Random;
 
 /**
  *
@@ -34,4 +35,6 @@ public interface EvalContext
 
   public Value getRowValue(String collectionName, String objName,
                            String colName);
+
+  public Random getRandom(Long seed);
 }

src/main/java/com/healthmarketscience/jackcess/impl/expr/BuiltinOperators.java

@@ -603,6 +603,10 @@ public class BuiltinOperators
     return new LongValue(s);
   }
 
+  public static Value toValue(float f) {
+    return new DoubleValue((double)f);
+  }
+
   public static Value toValue(Double s) {
     return new DoubleValue(s);
   }

src/main/java/com/healthmarketscience/jackcess/impl/expr/DefaultFunctions.java

@@ -35,7 +35,14 @@ public class DefaultFunctions
     new HashMap<String,Function>();
 
   private static final char NON_VAR_SUFFIX = '$';
-
+  static final RoundingMode DEFAULT_ROUND_MODE = RoundingMode.HALF_EVEN;
+  
+  static {
+    // load all default functions
+    DefaultTextFunctions.init();
+    DefaultNumberFunctions.init();
+  }
+  
   private DefaultFunctions() {}
 
   public static Function getFunction(String name) {
@@ -48,6 +55,11 @@ public class DefaultFunctions
     private final int _minParams;
     private final int _maxParams;
 
+    protected BaseFunction(String name)
+    {
+      this(name, 0, Integer.MAX_VALUE);
+    }
+
     protected BaseFunction(String name, int minParams, int maxParams)
     {
       _name = name;
@@ -75,6 +87,8 @@ public class DefaultFunctions
       }
     }
 
+    // FIXME, provide context for exceptions thrown
+    
     @Override
     public String toString() {
       return getName() + "()";
@@ -179,58 +193,6 @@ public class DefaultFunctions
     }
   });
 
-  public static final Function ASC = registerFunc(new Func1("Asc") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      int len = str.length();
-      if(len == 0) {
-        throw new IllegalStateException("No characters in string");
-      } 
-      long lv = str.charAt(0);
-      if((lv < 0) || (lv > 255)) {
-        throw new IllegalStateException("Character code '" + lv +
-                                        "' out of range ");
-      }
-      return BuiltinOperators.toValue(lv);
-    }
-  });
-
-  public static final Function ASCW = registerFunc(new Func1("AscW") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      int len = str.length();
-      if(len == 0) {
-        throw new IllegalStateException("No characters in string");
-      } 
-      long lv = str.charAt(0);
-      return BuiltinOperators.toValue(lv);
-    }
-  });
-
-  public static final Function CHR = registerStringFunc(new Func1("Chr") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      long lv = param1.getAsLong();
-      if((lv < 0) || (lv > 255)) {
-        throw new IllegalStateException("Character code '" + lv +
-                                        "' out of range ");
-      }
-      char[] cs = Character.toChars((int)lv);
-      return BuiltinOperators.toValue(new String(cs));
-    }
-  });
-
-  public static final Function CHRW = registerStringFunc(new Func1("ChrW") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      long lv = param1.getAsLong();
-      char[] cs = Character.toChars((int)lv);
-      return BuiltinOperators.toValue(new String(cs));
-    }
-  });
-
   public static final Function HEX = registerStringFunc(new Func1NullIsNull("Hex") {
     @Override
     protected Value eval1(EvalContext ctx, Value param1) {
@@ -272,18 +234,6 @@ public class DefaultFunctions
     }
   });
   
-  public static final Function STR = registerStringFunc(new Func1("Str") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      BigDecimal bd = param1.getAsBigDecimal();
-      String str = bd.toPlainString();
-      if(bd.compareTo(BigDecimal.ZERO) >= 0) {
-        str = " " + str;
-      }
-      return BuiltinOperators.toValue(str);
-    }
-  });
-
   public static final Function CBOOL = registerFunc(new Func1("CBool") {
     @Override
     protected Value eval1(EvalContext ctx, Value param1) {
@@ -307,7 +257,7 @@ public class DefaultFunctions
     @Override
     protected Value eval1(EvalContext ctx, Value param1) {
       BigDecimal bd = param1.getAsBigDecimal();
-      bd = bd.setScale(4, RoundingMode.HALF_EVEN);
+      bd = bd.setScale(4, DEFAULT_ROUND_MODE);
       return BuiltinOperators.toValue(bd);
     }
   });
@@ -317,7 +267,7 @@ public class DefaultFunctions
   //   protected Value eval1(EvalContext ctx, Value param1) {
   //   FIXME
   //     BigDecimal bd = param1.getAsBigDecimal();
-  //     bd.setScale(4, RoundingMode.HALF_EVEN);
+  //     bd.setScale(4, DEFAULT_ROUND_MODE);
   //     return BuiltinOperators.toValue(bd);
   //   }
   // });
@@ -325,8 +275,8 @@ public class DefaultFunctions
   public static final Function CDBL = registerFunc(new Func1("CDbl") {
     @Override
     protected Value eval1(EvalContext ctx, Value param1) {
-      Double db = param1.getAsDouble();
-      return BuiltinOperators.toValue(db);
+      Double dv = param1.getAsDouble();
+      return BuiltinOperators.toValue(dv);
     }
   });
 
@@ -363,11 +313,11 @@ public class DefaultFunctions
   public static final Function CSNG = registerFunc(new Func1("CSng") {
     @Override
     protected Value eval1(EvalContext ctx, Value param1) {
-      Double db = param1.getAsDouble();
-      if((db < Float.MIN_VALUE) || (db > Float.MAX_VALUE)) {
-        throw new IllegalStateException("Single value '" + db + "' out of range ");
+      Double dv = param1.getAsDouble();
+      if((dv < Float.MIN_VALUE) || (dv > Float.MAX_VALUE)) {
+        throw new IllegalStateException("Single value '" + dv + "' out of range ");
       }
-      return BuiltinOperators.toValue((double)db.floatValue());
+      return BuiltinOperators.toValue(dv.floatValue());
     }
   });
 
@@ -380,297 +330,23 @@ public class DefaultFunctions
 
   // FIXME, CVAR
 
-  public static final Function INSTR = registerFunc(new FuncVar("InStr", 2, 4) {
-    @Override
-    protected Value evalVar(EvalContext ctx, Value[] params) {
-      int idx = 0;
-      int start = 0;
-      if(params.length > 2) {
-        // 1 based offsets
-        start = params[0].getAsLong().intValue() - 1;
-        ++idx;
-      }
-      Value param1 = params[idx++];
-      if(param1.isNull()) {
-        return param1;
-      }
-      String s1 = param1.getAsString();
-      int s1Len = s1.length();
-      if(s1Len == 0) {
-        return BuiltinOperators.ZERO_VAL;
-      }
-      Value param2 = params[idx++];
-      if(param2.isNull()) {
-        return param2;
-      }
-      String s2 = param2.getAsString();
-      int s2Len = s2.length();
-      if(s2Len == 0) {
-        // 1 based offsets
-        return BuiltinOperators.toValue(start + 1);
-      }
-      boolean ignoreCase = true;
-      if(params.length > 3) {
-        ignoreCase = doIgnoreCase(params[3]);
-      }
-      int end = s1Len - s2Len;
-      while(start < end) {
-        if(s1.regionMatches(ignoreCase, start, s2, 0, s2Len)) {
-          // 1 based offsets
-          return BuiltinOperators.toValue(start + 1);
-        } 
-        ++start;
-      }
-      return BuiltinOperators.ZERO_VAL;
-    }
-  });
-
-  public static final Function INSTRREV = registerFunc(new FuncVar("InStrRev", 2, 4) {
-    @Override
-    protected Value evalVar(EvalContext ctx, Value[] params) {
-      Value param1 = params[0];
-      if(param1.isNull()) {
-        return param1;
-      }
-      String s1 = param1.getAsString();
-      int s1Len = s1.length();
-      if(s1Len == 0) {
-        return BuiltinOperators.ZERO_VAL;
-      }
-      Value param2 = params[1];
-      if(param2.isNull()) {
-        return param2;
-      }
-      String s2 = param2.getAsString();
-      int s2Len = s2.length();
-      int start = s1Len - 1;
-      if(s2Len == 0) {
-        // 1 based offsets
-        return BuiltinOperators.toValue(start + 1);
-      }
-      if(params.length > 2) {
-        start = params[2].getAsLong().intValue();
-        if(start == -1) {
-          start = s1Len;
-        } 
-        // 1 based offsets
-        --start;
-      }
-      boolean ignoreCase = true;
-      if(params.length > 3) {
-        ignoreCase = doIgnoreCase(params[3]);
-      }
-      start = Math.min(s1Len - s2Len, start);
-      while(start >= 0) {
-        if(s1.regionMatches(ignoreCase, start, s2, 0, s2Len)) {
-          // 1 based offsets
-          return BuiltinOperators.toValue(start + 1);
-        } 
-        --start;
-      }
-      return BuiltinOperators.ZERO_VAL;
-    }
-  });
-
-  public static final Function LCASE = registerStringFunc(new Func1NullIsNull("LCase") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(str.toLowerCase());
-    }
-  });
-
-  public static final Function UCASE = registerStringFunc(new Func1NullIsNull("UCase") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(str.toUpperCase());
-    }
-  });
-
-  public static final Function LEFT = registerStringFunc(new Func2("Left") {
-    @Override
-    protected Value eval2(EvalContext ctx, Value param1, Value param2) {
-      if(param1.isNull()) {
-        return param1;
-      }
-      String str = param1.getAsString();
-      int len = (int)Math.min(str.length(), param2.getAsLong());
-      return BuiltinOperators.toValue(str.substring(0, len));
-    }
-  });
-
-  public static final Function RIGHT = registerStringFunc(new Func2("Right") {
-    @Override
-    protected Value eval2(EvalContext ctx, Value param1, Value param2) {
-      if(param1.isNull()) {
-        return param1;
-      }
-      String str = param1.getAsString();
-      int strLen = str.length();
-      int len = (int)Math.min(strLen, param2.getAsLong());
-      return BuiltinOperators.toValue(str.substring(strLen - len, strLen));
-    }
-  });
-
-  public static final Function MID = registerStringFunc(new FuncVar("Mid", 2, 3) {
-    @Override
-    protected Value evalVar(EvalContext ctx, Value[] params) {
-      Value param1 = params[0];
-      if(param1.isNull()) {
-        return param1;
-      }
-      String str = param1.getAsString();
-      int strLen = str.length();
-      // 1 based offsets
-      int start = (int)Math.max(strLen, params[1].getAsLong() - 1);
-      int len = Math.max(
-          ((params.length > 2) ? params[2].getAsLong().intValue() : strLen),
-          (strLen - start));
-      return BuiltinOperators.toValue(str.substring(start, start + len));
-    }
-  });
-
-  public static final Function LEN = registerFunc(new Func1NullIsNull("Len") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(str.length());
-    }
-  });
-
-  public static final Function LTRIM = registerStringFunc(new Func1NullIsNull("LTrim") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(trim(str, true, false));
-    }
-  });
-
-  public static final Function RTRIM = registerStringFunc(new Func1NullIsNull("RTrim") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(trim(str, false, true));
-    }
-  });
-
-  public static final Function TRIM = registerStringFunc(new Func1NullIsNull("Trim") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(trim(str, true, true));
-    }
-  });
-
-  public static final Function SPACE = registerStringFunc(new Func1("Space") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      int lv = param1.getAsLong().intValue();
-      return BuiltinOperators.toValue(nchars(lv, ' '));
-    }
-  });
-
-  public static final Function STRCOMP = registerFunc(new FuncVar("StrComp", 2, 3) {
-    @Override
-    protected Value evalVar(EvalContext ctx, Value[] params) {
-      Value param1 = params[0];
-      Value param2 = params[1];
-      if(param1.isNull() || param2.isNull()) {
-        return BuiltinOperators.NULL_VAL;
-      }
-      String s1 = param1.getAsString();
-      String s2 = param2.getAsString();
-      boolean ignoreCase = true;
-      if(params.length > 2) {
-        ignoreCase = doIgnoreCase(params[2]);
-      }
-      int cmp = (ignoreCase ? 
-                 s1.compareToIgnoreCase(s2) : s1.compareTo(s2));
-      return BuiltinOperators.toValue(cmp);
-    }
-  });
-
-  public static final Function STRING = registerStringFunc(new Func2("String") {
-    @Override
-    protected Value eval2(EvalContext ctx, Value param1, Value param2) {
-      if(param1.isNull() || param2.isNull()) {
-        return BuiltinOperators.NULL_VAL;
-      }
-      int lv = param1.getAsLong().intValue();
-      char c = (char)(param2.getAsString().charAt(0) % 256);
-      return BuiltinOperators.toValue(nchars(lv, c));
-    }
-  });
-
-  public static final Function STRREVERSE = registerFunc(new Func1("StrReverse") {
-    @Override
-    protected Value eval1(EvalContext ctx, Value param1) {
-      String str = param1.getAsString();
-      return BuiltinOperators.toValue(
-          new StringBuilder(str).reverse().toString());
-    }
-  });
-
-
-  private static String nchars(int num, char c) {
-    StringBuilder sb = new StringBuilder(num);
-    for(int i = 0; i < num; ++i) {
-      sb.append(c);
-    }
-    return sb.toString();
-  }
-
-  private static String trim(String str, boolean doLeft, boolean doRight) {
-    int start = 0;
-    int end = str.length();
-
-    if(doLeft) {
-      while((start < end) && (str.charAt(start) == ' ')) {
-        ++start;
-      }
-    } 
-    if(doRight) {
-      while((start < end) && (str.charAt(end - 1) == ' ')) {
-        --end;
-      }
-    }
-    return str.substring(start, end);
-  }
-
-  private static boolean doIgnoreCase(Value paramCmp) {
-    int cmpType = paramCmp.getAsLong().intValue();
-    switch(cmpType) {
-    case -1:
-      // vbUseCompareOption -> default is binary
-    case 0:
-      // vbBinaryCompare
-      return false;
-    case 1:
-      // vbTextCompare
-      return true;
-    default:
-      // vbDatabaseCompare -> unsupported
-      throw new IllegalStateException("Unsupported compare type " + cmpType);
-    } 
-  }
 
   private static long roundToLong(Value param) {
     if(param.getType().isIntegral()) {
       return param.getAsLong();
     }
-    return param.getAsBigDecimal().setScale(0, RoundingMode.HALF_EVEN)
+    return param.getAsBigDecimal().setScale(0, DEFAULT_ROUND_MODE)
       .longValue();
   }
 
   // https://www.techonthenet.com/access/functions/
   // https://support.office.com/en-us/article/Access-Functions-by-category-b8b136c3-2716-4d39-94a2-658ce330ed83
 
-  private static Function registerFunc(Function func) {
+  static Function registerFunc(Function func) {
     return registerFunc(false, func);
   }
 
-  private static Function registerStringFunc(Function func) {
+  static Function registerStringFunc(Function func) {
     return registerFunc(true, func);
   }
 

src/main/java/com/healthmarketscience/jackcess/impl/expr/DefaultNumberFunctions.java

@@ -0,0 +1,182 @@
+/*
+Copyright (c) 2017 James Ahlborn
+
+Licensed 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 com.healthmarketscience.jackcess.impl.expr;
+
+import java.math.BigDecimal;
+
+import com.healthmarketscience.jackcess.expr.EvalContext;
+import com.healthmarketscience.jackcess.expr.Function;
+import com.healthmarketscience.jackcess.expr.Value;
+import static com.healthmarketscience.jackcess.impl.expr.DefaultFunctions.*;
+
+/**
+ *
+ * @author James Ahlborn
+ */
+public class DefaultNumberFunctions 
+{
+
+  private DefaultNumberFunctions() {}
+
+  static void init() {
+    // dummy method to ensure this class is loaded
+  }
+  
+  public static final Function ABS = registerFunc(new Func1NullIsNull("Abs") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      Value.Type type = param1.getType();
+      if(!type.isNumeric()) {
+        // FIXME how to handle text/date?
+        // FIXME, cast to number, date as date?
+      }
+      if(type.isIntegral()) {
+        return BuiltinOperators.toValue(Math.abs(param1.getAsLong()));
+      }
+      if(type.getPreferredFPType() == Value.Type.DOUBLE) {
+        return BuiltinOperators.toValue(Math.abs(param1.getAsDouble()));
+      }
+      return BuiltinOperators.toValue(param1.getAsBigDecimal().abs());
+    }
+  });
+
+  public static final Function ATAN = registerFunc(new Func1("Atan") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      Value.Type type = param1.getType();
+      if(!type.isNumeric()) {
+        // FIXME how to handle text/date?
+      }
+      return BuiltinOperators.toValue(Math.atan(param1.getAsDouble()));
+    }
+  });
+
+  public static final Function COS = registerFunc(new Func1("Cos") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      Value.Type type = param1.getType();
+      if(!type.isNumeric()) {
+        // FIXME how to handle text/date?
+      }
+      return BuiltinOperators.toValue(Math.cos(param1.getAsDouble()));
+    }
+  });
+
+  public static final Function EXP = registerFunc(new Func1("Exp") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      Value.Type type = param1.getType();
+      if(!type.isNumeric()) {
+        // FIXME how to handle text/date?
+      }
+      return BuiltinOperators.toValue(Math.exp(param1.getAsDouble()));
+    }
+  });
+
+  public static final Function FIX = registerFunc(new Func1NullIsNull("Fix") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      Value.Type type = param1.getType();
+      if(!type.isNumeric()) {
+        // FIXME how to handle text/date?
+      }
+      if(type.isIntegral()) {
+        return param1;
+      }
+      return BuiltinOperators.toValue(param1.getAsDouble().longValue());
+    }
+  });
+
+  public static final Function INT = registerFunc(new Func1NullIsNull("Int") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      Value.Type type = param1.getType();
+      if(!type.isNumeric()) {
+        // FIXME how to handle text/date?
+      }
+      if(type.isIntegral()) {
+        return param1;
+      }
+      return BuiltinOperators.toValue((long)Math.floor(param1.getAsDouble()));
+    }
+  });
+
+  public static final Function RND = registerFunc(new FuncVar("Rnd", 0, 1) {
+    @Override
+    public boolean isPure() {
+      return false;
+    }
+    @Override
+    protected Value evalVar(EvalContext ctx, Value[] params) {
+      Long seed = ((params.length > 0) ? params[0].getAsLong() : null);
+      return BuiltinOperators.toValue(ctx.getRandom(seed).nextFloat());
+    }
+  });
+
+  public static final Function ROUND = registerFunc(new FuncVar("Round", 1, 2) {
+    @Override
+    protected Value evalVar(EvalContext ctx, Value[] params) {
+      Value param1 = params[0];
+      if(param1.isNull()) {
+        return null;
+      }
+      if(param1.getType().isIntegral()) {
+        return param1;
+      }
+      int scale = 0;
+      if(params.length > 1) {
+        scale = params[1].getAsLong().intValue();
+      }
+      BigDecimal bd = param1.getAsBigDecimal().setScale(scale, DEFAULT_ROUND_MODE);
+      return BuiltinOperators.toValue(bd);
+    }
+  });
+
+  public static final Function SGN = registerFunc(new Func1NullIsNull("Sgn") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      int signum = 0;
+      if(param1.getType().isIntegral()) {
+        long lv = param1.getAsLong();
+        signum = ((lv > 0) ? 1 : ((lv < 0) ? -1 : 0));
+      } else {
+        signum = param1.getAsBigDecimal().signum();
+      }
+      return BuiltinOperators.toValue(signum);
+    }
+  });
+
+  public static final Function SQR = registerFunc(new Func1("Sqr") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      double dv = param1.getAsDouble();
+      if(dv < 0.0d) {
+        throw new IllegalStateException("Invalid value '" + dv + "'");
+      }
+      return BuiltinOperators.toValue(Math.sqrt(dv));
+    }
+  });
+
+  // public static final Function Val = registerFunc(new Func1("Val") {
+  //   @Override
+  //   protected Value eval1(EvalContext ctx, Value param1) {
+  //     // FIXME, maybe leverage ExpressionTokenizer.maybeParseNumberLiteral (note, leading - or + is valid, exponent form is valid)
+  //   }
+  // });
+
+
+}

src/main/java/com/healthmarketscience/jackcess/impl/expr/DefaultTextFunctions.java

@@ -0,0 +1,379 @@
+/*
+Copyright (c) 2017 James Ahlborn
+
+Licensed 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 com.healthmarketscience.jackcess.impl.expr;
+
+import java.math.BigDecimal;
+
+import com.healthmarketscience.jackcess.expr.EvalContext;
+import com.healthmarketscience.jackcess.expr.Function;
+import com.healthmarketscience.jackcess.expr.Value;
+import static com.healthmarketscience.jackcess.impl.expr.DefaultFunctions.*;
+
+/**
+ *
+ * @author James Ahlborn
+ */
+public class DefaultTextFunctions 
+{
+
+  private DefaultTextFunctions() {}
+
+  static void init() {
+    // dummy method to ensure this class is loaded
+  }
+  
+  public static final Function ASC = registerFunc(new Func1("Asc") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      int len = str.length();
+      if(len == 0) {
+        throw new IllegalStateException("No characters in string");
+      } 
+      long lv = str.charAt(0);
+      if((lv < 0) || (lv > 255)) {
+        throw new IllegalStateException("Character code '" + lv +
+                                        "' out of range ");
+      }
+      return BuiltinOperators.toValue(lv);
+    }
+  });
+
+  public static final Function ASCW = registerFunc(new Func1("AscW") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      int len = str.length();
+      if(len == 0) {
+        throw new IllegalStateException("No characters in string");
+      } 
+      long lv = str.charAt(0);
+      return BuiltinOperators.toValue(lv);
+    }
+  });
+
+  public static final Function CHR = registerStringFunc(new Func1("Chr") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      long lv = param1.getAsLong();
+      if((lv < 0) || (lv > 255)) {
+        throw new IllegalStateException("Character code '" + lv +
+                                        "' out of range ");
+      }
+      char[] cs = Character.toChars((int)lv);
+      return BuiltinOperators.toValue(new String(cs));
+    }
+  });
+
+  public static final Function CHRW = registerStringFunc(new Func1("ChrW") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      long lv = param1.getAsLong();
+      char[] cs = Character.toChars((int)lv);
+      return BuiltinOperators.toValue(new String(cs));
+    }
+  });
+
+  public static final Function STR = registerStringFunc(new Func1("Str") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      BigDecimal bd = param1.getAsBigDecimal();
+      String str = bd.toPlainString();
+      if(bd.compareTo(BigDecimal.ZERO) >= 0) {
+        str = " " + str;
+      }
+      return BuiltinOperators.toValue(str);
+    }
+  });
+
+  public static final Function INSTR = registerFunc(new FuncVar("InStr", 2, 4) {
+    @Override
+    protected Value evalVar(EvalContext ctx, Value[] params) {
+      int idx = 0;
+      int start = 0;
+      if(params.length > 2) {
+        // 1 based offsets
+        start = params[0].getAsLong().intValue() - 1;
+        ++idx;
+      }
+      Value param1 = params[idx++];
+      if(param1.isNull()) {
+        return param1;
+      }
+      String s1 = param1.getAsString();
+      int s1Len = s1.length();
+      if(s1Len == 0) {
+        return BuiltinOperators.ZERO_VAL;
+      }
+      Value param2 = params[idx++];
+      if(param2.isNull()) {
+        return param2;
+      }
+      String s2 = param2.getAsString();
+      int s2Len = s2.length();
+      if(s2Len == 0) {
+        // 1 based offsets
+        return BuiltinOperators.toValue(start + 1);
+      }
+      boolean ignoreCase = true;
+      if(params.length > 3) {
+        ignoreCase = doIgnoreCase(params[3]);
+      }
+      int end = s1Len - s2Len;
+      while(start < end) {
+        if(s1.regionMatches(ignoreCase, start, s2, 0, s2Len)) {
+          // 1 based offsets
+          return BuiltinOperators.toValue(start + 1);
+        } 
+        ++start;
+      }
+      return BuiltinOperators.ZERO_VAL;
+    }
+  });
+
+  public static final Function INSTRREV = registerFunc(new FuncVar("InStrRev", 2, 4) {
+    @Override
+    protected Value evalVar(EvalContext ctx, Value[] params) {
+      Value param1 = params[0];
+      if(param1.isNull()) {
+        return param1;
+      }
+      String s1 = param1.getAsString();
+      int s1Len = s1.length();
+      if(s1Len == 0) {
+        return BuiltinOperators.ZERO_VAL;
+      }
+      Value param2 = params[1];
+      if(param2.isNull()) {
+        return param2;
+      }
+      String s2 = param2.getAsString();
+      int s2Len = s2.length();
+      int start = s1Len - 1;
+      if(s2Len == 0) {
+        // 1 based offsets
+        return BuiltinOperators.toValue(start + 1);
+      }
+      if(params.length > 2) {
+        start = params[2].getAsLong().intValue();
+        if(start == -1) {
+          start = s1Len;
+        } 
+        // 1 based offsets
+        --start;
+      }
+      boolean ignoreCase = true;
+      if(params.length > 3) {
+        ignoreCase = doIgnoreCase(params[3]);
+      }
+      start = Math.min(s1Len - s2Len, start);
+      while(start >= 0) {
+        if(s1.regionMatches(ignoreCase, start, s2, 0, s2Len)) {
+          // 1 based offsets
+          return BuiltinOperators.toValue(start + 1);
+        } 
+        --start;
+      }
+      return BuiltinOperators.ZERO_VAL;
+    }
+  });
+
+  public static final Function LCASE = registerStringFunc(new Func1NullIsNull("LCase") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(str.toLowerCase());
+    }
+  });
+
+  public static final Function UCASE = registerStringFunc(new Func1NullIsNull("UCase") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(str.toUpperCase());
+    }
+  });
+
+  public static final Function LEFT = registerStringFunc(new Func2("Left") {
+    @Override
+    protected Value eval2(EvalContext ctx, Value param1, Value param2) {
+      if(param1.isNull()) {
+        return param1;
+      }
+      String str = param1.getAsString();
+      int len = (int)Math.min(str.length(), param2.getAsLong());
+      return BuiltinOperators.toValue(str.substring(0, len));
+    }
+  });
+
+  public static final Function RIGHT = registerStringFunc(new Func2("Right") {
+    @Override
+    protected Value eval2(EvalContext ctx, Value param1, Value param2) {
+      if(param1.isNull()) {
+        return param1;
+      }
+      String str = param1.getAsString();
+      int strLen = str.length();
+      int len = (int)Math.min(strLen, param2.getAsLong());
+      return BuiltinOperators.toValue(str.substring(strLen - len, strLen));
+    }
+  });
+
+  public static final Function MID = registerStringFunc(new FuncVar("Mid", 2, 3) {
+    @Override
+    protected Value evalVar(EvalContext ctx, Value[] params) {
+      Value param1 = params[0];
+      if(param1.isNull()) {
+        return param1;
+      }
+      String str = param1.getAsString();
+      int strLen = str.length();
+      // 1 based offsets
+      int start = (int)Math.max(strLen, params[1].getAsLong() - 1);
+      int len = Math.max(
+          ((params.length > 2) ? params[2].getAsLong().intValue() : strLen),
+          (strLen - start));
+      return BuiltinOperators.toValue(str.substring(start, start + len));
+    }
+  });
+
+  public static final Function LEN = registerFunc(new Func1NullIsNull("Len") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(str.length());
+    }
+  });
+
+  public static final Function LTRIM = registerStringFunc(new Func1NullIsNull("LTrim") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(trim(str, true, false));
+    }
+  });
+
+  public static final Function RTRIM = registerStringFunc(new Func1NullIsNull("RTrim") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(trim(str, false, true));
+    }
+  });
+
+  public static final Function TRIM = registerStringFunc(new Func1NullIsNull("Trim") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(trim(str, true, true));
+    }
+  });
+
+  public static final Function SPACE = registerStringFunc(new Func1("Space") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      int lv = param1.getAsLong().intValue();
+      return BuiltinOperators.toValue(nchars(lv, ' '));
+    }
+  });
+
+  public static final Function STRCOMP = registerFunc(new FuncVar("StrComp", 2, 3) {
+    @Override
+    protected Value evalVar(EvalContext ctx, Value[] params) {
+      Value param1 = params[0];
+      Value param2 = params[1];
+      if(param1.isNull() || param2.isNull()) {
+        return BuiltinOperators.NULL_VAL;
+      }
+      String s1 = param1.getAsString();
+      String s2 = param2.getAsString();
+      boolean ignoreCase = true;
+      if(params.length > 2) {
+        ignoreCase = doIgnoreCase(params[2]);
+      }
+      int cmp = (ignoreCase ? 
+                 s1.compareToIgnoreCase(s2) : s1.compareTo(s2));
+      return BuiltinOperators.toValue(cmp);
+    }
+  });
+
+  public static final Function STRING = registerStringFunc(new Func2("String") {
+    @Override
+    protected Value eval2(EvalContext ctx, Value param1, Value param2) {
+      if(param1.isNull() || param2.isNull()) {
+        return BuiltinOperators.NULL_VAL;
+      }
+      int lv = param1.getAsLong().intValue();
+      char c = (char)(param2.getAsString().charAt(0) % 256);
+      return BuiltinOperators.toValue(nchars(lv, c));
+    }
+  });
+
+  public static final Function STRREVERSE = registerFunc(new Func1("StrReverse") {
+    @Override
+    protected Value eval1(EvalContext ctx, Value param1) {
+      String str = param1.getAsString();
+      return BuiltinOperators.toValue(
+          new StringBuilder(str).reverse().toString());
+    }
+  });
+
+  
+  private static String nchars(int num, char c) {
+    StringBuilder sb = new StringBuilder(num);
+    for(int i = 0; i < num; ++i) {
+      sb.append(c);
+    }
+    return sb.toString();
+  }
+
+  private static String trim(String str, boolean doLeft, boolean doRight) {
+    int start = 0;
+    int end = str.length();
+
+    if(doLeft) {
+      while((start < end) && (str.charAt(start) == ' ')) {
+        ++start;
+      }
+    } 
+    if(doRight) {
+      while((start < end) && (str.charAt(end - 1) == ' ')) {
+        --end;
+      }
+    }
+    return str.substring(start, end);
+  }
+
+  private static boolean doIgnoreCase(Value paramCmp) {
+    int cmpType = paramCmp.getAsLong().intValue();
+    switch(cmpType) {
+    case -1:
+      // vbUseCompareOption -> default is binary
+    case 0:
+      // vbBinaryCompare
+      return false;
+    case 1:
+      // vbTextCompare
+      return true;
+    default:
+      // vbDatabaseCompare -> unsupported
+      throw new IllegalStateException("Unsupported compare type " + cmpType);
+    } 
+  }
+
+  
+}

src/test/java/com/healthmarketscience/jackcess/impl/expr/ExpressionatorTest.java

@@ -18,6 +18,7 @@ package com.healthmarketscience.jackcess.impl.expr;
 
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.Random;
 
 import com.healthmarketscience.jackcess.DatabaseBuilder;
 import com.healthmarketscience.jackcess.TestUtil;
@@ -349,6 +350,9 @@ public class ExpressionatorTest extends TestCase
   private static final class TestEvalContext implements EvalContext
   {
     private final Value _thisVal;
+    private Random _defRnd;
+    private Random _rnd;
+    private long _rndSeed;
 
     private TestEvalContext(Value thisVal) {
       _thisVal = thisVal;
@@ -379,5 +383,19 @@ public class ExpressionatorTest extends TestCase
                              String colName) {
       throw new UnsupportedOperationException();
     }
+
+    public Random getRandom(Long seed) {
+      if(seed == null) {
+        if(_defRnd == null) {
+          _defRnd = new Random(System.currentTimeMillis());
+        }
+        return _defRnd;
+      }
+      if((_rnd == null) || (seed != _rndSeed)) {
+        _rndSeed = seed;
+        _rnd = new Random(_rndSeed);
+      }
+      return _rnd;
+    } 
   }
 }