[#87] Provide support for major-version based config files

This commit introduces the possibility to handle per-major-version
configuration files (e.g., `17.conf`) that are loaded in the case the
version specific file (.e.g., `17.1.conf`) is not found on the system.

The loading of a configuration file gives priority to the exact
version, so for instance `17.1.conf`, then if such file is not found
the program tries to load a `17.conf` (i.e., major mode file), and at
last the `default.conf` file.

Bump version to 1.3.9

Close #87

bin/pgenv

@@ -2,7 +2,7 @@
 #
 # VERSION
 #
-PGENV_VERSION="1.3.8"
+PGENV_VERSION="1.3.9"
 
 # https://stackoverflow.com/a/19622569/79202
 trap 'exit' ERR
@@ -559,21 +559,47 @@ pgenv_configuration_dump_or_exit(){
 # will be 'sourced' into the current script runtime.
 #
 # The function accepts an optional argument which is the version number
-# to search for. A configuration file with such version number
-# will be used as configuration, and in the case it is missing, the default
-# configuration file will be used.
+# in the format <major>.<minor>.
+# The function searches for files in this order:
+# - if a version number has been specified, searches for the <major>.<minor>.conf file
+# - if the above is not found, it searches for <major>.conf file
+# - if the above is not found or no version has been specified, it searches for the default.conf
+#   file.
+#
+# This means that, for instance, specifying the version as 17.2 makes the files to be selected
+# in the following order of preference:
+# - 17.2.conf
+# - 17.conf
+# - default.conf
+#
+# The first file found is used to load the configuration from.
 #
 # The function sets the PGENV_CONFIGURATION_FILE variable to the name of the
 # file loaded or to an empty string. This helps understanding later on
 # if the configuration has been loaded.
 pgenv_configuration_load(){
     local v=$1
+    local major
+
+    # extract the major version of PostgreSQL
+    if [[ "$v" =~ ^([[:digit:]]+) ]]; then
+	major="${BASH_REMATCH[1]}"
+    fi
+
+    if [ $major -lt 10 ]; then
+	# here the major version is made by two numbers, e.g., 9.6
+	if [[ "$v" =~ ^([[:digit:]].[[:digit:]]) ]]; then
+	    major="${BASH_REMATCH[1]}"
+	fi
+    fi
+
 
     local PGENV_DEFAULT_CONFIG_FILE=$( pgenv_configuration_file_name )
+    local PGENV_MAJOR_CONFIG_FILE=$( pgenv_configuration_file_name $major )
     local PGENV_CONFIG_FILE=$( pgenv_configuration_file_name $v )
     PGENV_CONFIGURATION_FILE=''
 
-    for conf in $( echo "$PGENV_CONFIG_FILE" "$PGENV_DEFAULT_CONFIG_FILE" )
+    for conf in $( echo "$PGENV_CONFIG_FILE" "$PGENV_MAJOR_CONFIG_FILE" "$PGENV_DEFAULT_CONFIG_FILE" )
     do
         pgenv_debug "Looking for configuration in $conf"