Allow config file to load custom data files

The parameters "custom_unit_file", "custom_dimension_file" and
"custom_exception_file" can now be used to load custom unit, dimension
and exception files.  Specify them more than once to load multiple
files.

I haven't yet added this to the GUI, and I probably won't, because you
already need to be able to edit text files to create this, so having a
GUI won't make it any more intuitive.

2 files changed, 22 insertions, 6 deletions

diff --git a/docs/roadmap.org b/docs/roadmap.org
index a68dae5..c57fb2a 100644
--- a/docs/roadmap.org
+++ b/docs/roadmap.org
@@ -17,7 +17,6 @@ Feature Requirements:
 
 Data/Configuration Requirements:
 - All of the data formats (e.g. unit files) should be standardized.
-- The config file should be able to specify the location of the data files.
 
 Documentation/Testing Requirements:
 - 7Units should be fully documented.
diff --git a/src/main/java/sevenUnitsGUI/Presenter.java b/src/main/java/sevenUnitsGUI/Presenter.java
index 3ecfba6..e471b01 100644
--- a/src/main/java/sevenUnitsGUI/Presenter.java
+++ b/src/main/java/sevenUnitsGUI/Presenter.java
@@ -21,7 +21,6 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
@@ -73,16 +72,16 @@ public final class Presenter {
 		if (System.getProperty("os.name").startsWith("Windows")) {
 			final String envFolder = System.getenv("LOCALAPPDATA");
 			if (envFolder == null || "".equals(envFolder)) {
-				configDir = Paths.get(System.getenv("USERPROFILE"), "AppData", "Local", "SevenUnits");
+				configDir = Path.of(System.getenv("USERPROFILE"), "AppData", "Local", "SevenUnits");
 			} else {
-				configDir = Paths.get(envFolder, "SevenUnits");
+				configDir = Path.of(envFolder, "SevenUnits");
 			}
 		} else {
 			final String envFolder = System.getenv("XDG_CONFIG_HOME");
 			if (envFolder == null || "".equals(envFolder)) {
-				configDir = Paths.get(System.getenv("HOME"), ".config", "SevenUnits");
+				configDir = Path.of(System.getenv("HOME"), ".config", "SevenUnits");
 			} else {
-				configDir = Paths.get(envFolder, "SevenUnits");
+				configDir = Path.of(envFolder, "SevenUnits");
 			}
 		}
 
@@ -99,6 +98,13 @@ public final class Presenter {
 		return Optional.of(configDir.resolve("config.txt"));
 	}
 
+	/** Gets a Path from a pathname in the config file. */
+	private static Path pathFromConfig(String pathname) {
+		return CONFIG_FILE.map(configFile ->
+			configFile.getParent().resolve(pathname)
+		).orElse(Path.of(pathname));
+	}
+
 	/**
 	 * Adds default units and dimensions to a database.
 	 * 
@@ -615,6 +621,17 @@ public final class Presenter {
 				switch (param) {
 				// set manually to avoid the unnecessary saving of the non-manual
 				// methods
+				case "custom_dimension_file":
+					this.database.loadDimensionFile(pathFromConfig(value));
+					break;
+				case "custom_exception_file":
+					Files.lines(pathFromConfig(value))
+						.map(Presenter::withoutComments)
+						.forEach(this.metricExceptions::add);
+					break;
+				case "custom_unit_file":
+					this.database.loadUnitsFile(pathFromConfig(value));
+					break;
 				case "number_display_rule":
 					this.numberDisplayRule = StandardDisplayRules
 							.getStandardRule(value);