[PATCH 09/13] value-labels: New function val_labs_find_value().

[Ben Pfaff]

The new data sheet implementation (in an upcoming commit) will use
this.
---
 src/data/value-labels.c |   31 ++++++++++++++++++++++++++++++-
 src/data/value-labels.h |    4 +++-
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/data/value-labels.c b/src/data/value-labels.c
index 746e209..0b2ae3f 100644
--- a/src/data/value-labels.c
+++ b/src/data/value-labels.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 1997-9, 2000, 2009, 2010, 2011 Free Software Foundation, Inc.
+   Copyright (C) 1997-9, 2000, 2009, 2010, 2011, 2012 Free Software 
Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -256,6 +256,35 @@ val_labs_lookup (const struct val_labs *vls, const union 
value *value)
   return (vls == NULL ? NULL
           : val_labs_lookup__ (vls, value, value_hash (value, vls->width, 0)));
 }
+
+/* Searches VLS for a value label whose label is exactly LABEL.  If successful,
+   returns the corresponding value.  Otherwise, returns a null pointer.
+
+   Returns a null pointer if VLS is null.
+
+   This function is O(n) in the number of labels in VLS. */
+const union value *
+val_labs_find_value (const struct val_labs *vls, const char *label_)
+{
+  const union value *value = NULL;
+
+  if (vls != NULL)
+    {
+      const struct val_lab *vl;
+      const char *label;
+
+      label = intern_new (label_);
+      HMAP_FOR_EACH (vl, struct val_lab, node, &vls->labels)
+        if (vl->label == label)
+          {
+            value = &vl->value;
+            break;
+          }
+      intern_unref (label);
+    }
+
+  return value;
+}
 
 /* Returns the first value label in VLS, in arbitrary order, or a
    null pointer if VLS is empty or if VLS is a null pointer.  If
diff --git a/src/data/value-labels.h b/src/data/value-labels.h
index f0f7ce0..af98d9f 100644
--- a/src/data/value-labels.h
+++ b/src/data/value-labels.h
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 1997-9, 2000, 2009, 2011 Free Software Foundation, Inc.
+   Copyright (C) 1997-9, 2000, 2009, 2011, 2012 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -93,6 +93,8 @@ size_t val_labs_count (const struct val_labs *);
 const char *val_labs_find (const struct val_labs *, const union value *);
 struct val_lab *val_labs_lookup (const struct val_labs *,
                                  const union value *);
+const union value *val_labs_find_value (const struct val_labs *,
+                                        const char *label);
 
 /* Basic properties. */
 size_t val_labs_count (const struct val_labs *);
-- 
1.7.2.5