First commit

config.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"ccat/stack"
+	"os"
+	"regexp"
+	"strings"
+
+	"gopkg.in/yaml.v2"
+)
+
+// loadConfig takes in the filename of a config file. It reads the file,
+// and returns a stack of RegColors, with the item at the bottom being the one that
+// was read first. This ensures that, _when accessing the RegColors in the stack, the last
+// one (ie. the one that was read first) has highest precedence_.
+// If there is an error compiling the regular expressions, the error is returned.
+func loadConfig(configFilename string) (stack.Stack[regColor], error) {
+	configFile, err := os.ReadFile(configFilename)
+	if err != nil {
+		panic(err)
+	}
+
+	// Here, I create a MapSlice. This is a slice of key-value pairs, and will
+	// store the results of unmarshalling the YAML file.
+	tempMapSlice := yaml.MapSlice{}
+	if err := yaml.Unmarshal(configFile, &tempMapSlice); err != nil {
+		panic(err)
+	}
+
+	// Here, I create the stack which will eventually be returned.
+	// Each element of the MapSlice (created above) stores the key and value of a line
+	// in the file.
+	// Each regex string is compiled, and if there is an error, that error is
+	//  returned.
+	regColorStack := stack.NewStack[regColor](len(strings.Split(string(configFile), "\n"))) // The stack will have the same size as the number of lines in the file
+	for _, item := range tempMapSlice {
+		re := regexp.MustCompile(item.Key.(string))
+		clr, err := newColor(item.Value.(string))
+		if err != nil {
+			panic(err)
+		}
+		// If we got past the panic, then the color _must_ be valid.
+		regColorStack.Push(regColor{re, clr})
+	}
+
+	return *regColorStack, nil
+}