From 9c68929213e0995bcf533c1111cd733ffd472bb9 Mon Sep 17 00:00:00 2001
From: Par Winzell <zell@threerings.net>
Date: Wed, 9 Sep 2009 19:51:33 +0000
Subject: [PATCH] It turns out PostgreSQL supports LN(exp) and LOG(exp) in
 double precision, but not LOG(base, exp). So we're adding an explicit LOG10.
 I wonder how useful the two-argument one is... maybe we should delete it.

---
 src/java/com/samskivert/depot/Funs.java             | 13 ++++++++-----
 .../com/samskivert/depot/function/NumericalFun.java |  9 +++++++++
 .../com/samskivert/depot/impl/BuildVisitor.java     |  6 ++++++
 .../samskivert/depot/impl/ExpressionVisitor.java    |  2 ++
 .../samskivert/depot/impl/PostgreSQLBuilder.java    |  3 ++-
 5 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/java/com/samskivert/depot/Funs.java b/src/java/com/samskivert/depot/Funs.java
index 9677d7d..d27dbc8 100644
--- a/src/java/com/samskivert/depot/Funs.java
+++ b/src/java/com/samskivert/depot/Funs.java
@@ -68,7 +68,8 @@ public class Funs
     }
 
     /**
-     * Creates an expression that computes the natural logarithm of the supplied expression.
+     * Creates an expression that computes the natural logarithm of the supplied expression,
+     * which may be double-precision.
      */
     public static Ln ln (SQLExpression exp)
     {
@@ -76,16 +77,18 @@ public class Funs
     }
 
     /**
-     * Creates an expression that computes the base-10 logarithm of the supplied expression.
+     * Creates an expression that computes the base-10 logarithm of the supplied expression,
+     * which may be double-precision.
      */
-    public static LogN log10 (SQLExpression value)
+    public static Log10 log10 (SQLExpression value)
     {
-        return new LogN(Exps.value(10), value);
+        return new Log10(value);
     }
 
     /**
      * Creates an expression that computes the logarithm of the supplied value expression
-     * in the supplied base expression.
+     * in the supplied base expression. Note: Under PostgreSQL, this must evaluate to a simple
+     * numerical, not double precision.
      */
     public static LogN logN (SQLExpression base, SQLExpression value)
     {
diff --git a/src/java/com/samskivert/depot/function/NumericalFun.java b/src/java/com/samskivert/depot/function/NumericalFun.java
index 1cd2179..e3c9540 100644
--- a/src/java/com/samskivert/depot/function/NumericalFun.java
+++ b/src/java/com/samskivert/depot/function/NumericalFun.java
@@ -70,6 +70,15 @@ public abstract class NumericalFun
         }
     }
 
+    public static class Log10 extends OneArgFun {
+        public Log10 (SQLExpression value) {
+            super(value);
+        }
+        public Object accept (ExpressionVisitor<?> visitor) {
+            return visitor.visit(this);
+        }
+    }
+
     public static class LogN extends TwoArgFun {
         public LogN (SQLExpression base, SQLExpression value) {
             super(base, value);
diff --git a/src/java/com/samskivert/depot/impl/BuildVisitor.java b/src/java/com/samskivert/depot/impl/BuildVisitor.java
index d770c15..a20753e 100644
--- a/src/java/com/samskivert/depot/impl/BuildVisitor.java
+++ b/src/java/com/samskivert/depot/impl/BuildVisitor.java
@@ -68,6 +68,7 @@ import com.samskivert.depot.function.NumericalFun.Ceil;
 import com.samskivert.depot.function.NumericalFun.Exp;
 import com.samskivert.depot.function.NumericalFun.Floor;
 import com.samskivert.depot.function.NumericalFun.Ln;
+import com.samskivert.depot.function.NumericalFun.Log10;
 import com.samskivert.depot.function.NumericalFun.LogN;
 import com.samskivert.depot.function.NumericalFun.Pi;
 import com.samskivert.depot.function.NumericalFun.Power;
@@ -617,6 +618,11 @@ public abstract class BuildVisitor implements ExpressionVisitor<Void>
         return appendFunctionCall("ln", exp.getArg());
     }
 
+    public Void visit (Log10 exp)
+    {
+        return appendFunctionCall("log", exp.getArg());
+    }
+
     public Void visit (LogN exp)
     {
         return appendFunctionCall("log", exp.getBase(), exp.getValue());
diff --git a/src/java/com/samskivert/depot/impl/ExpressionVisitor.java b/src/java/com/samskivert/depot/impl/ExpressionVisitor.java
index dcd9b19..98da311 100644
--- a/src/java/com/samskivert/depot/impl/ExpressionVisitor.java
+++ b/src/java/com/samskivert/depot/impl/ExpressionVisitor.java
@@ -51,6 +51,7 @@ import com.samskivert.depot.function.NumericalFun.Ceil;
 import com.samskivert.depot.function.NumericalFun.Exp;
 import com.samskivert.depot.function.NumericalFun.Floor;
 import com.samskivert.depot.function.NumericalFun.Ln;
+import com.samskivert.depot.function.NumericalFun.Log10;
 import com.samskivert.depot.function.NumericalFun.LogN;
 import com.samskivert.depot.function.NumericalFun.Pi;
 import com.samskivert.depot.function.NumericalFun.Power;
@@ -123,6 +124,7 @@ public interface ExpressionVisitor<T>
     public T visit (Exp exp);
     public T visit (Floor exp);
     public T visit (Ln exp);
+    public T visit (Log10 exp);
     public T visit (LogN exp);
     public T visit (Pi exp);
     public T visit (Power exp);
diff --git a/src/java/com/samskivert/depot/impl/PostgreSQLBuilder.java b/src/java/com/samskivert/depot/impl/PostgreSQLBuilder.java
index a13f0f6..218bf28 100644
--- a/src/java/com/samskivert/depot/impl/PostgreSQLBuilder.java
+++ b/src/java/com/samskivert/depot/impl/PostgreSQLBuilder.java
@@ -86,7 +86,8 @@ public class PostgreSQLBuilder
             return null;
         }
 
-        @Override public Void visit (DatePart exp) {
+        @Override public Void visit (DatePart exp)
+        {
             return appendFunctionCall(
                 "date_part", Exps.value(translateDatePart(exp.getPart())), exp.getArg());
         }