Updated some regexes for markdown coloring

One of the expressions used .* to mean 'any character except newline', but since I've
enabled 'RE_SINGLE_LINE' mode, a dot matches a newline as well.

.gitignore

@@ -1,2 +1,3 @@
 ccat
+*.zip
 

LICENSE.md

@@ -0,0 +1,8 @@
+Copyright 2025 Aadhavan Srinivasan
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+

README.md

@@ -0,0 +1,73 @@
+## ccat
+
+ccat is a file printing tool (like 'cat') which uses Regular Expressions to enable syntax highlighting.
+
+---
+
+### Features
+- 11 colors are defined out-of-the-box: RED, BLUE, GREEN, MAGENTA, CYAN, BLACK, WHITE, YELLOW, GRAY, ORANGE and DARKBLUE.
+- Support for defining custom colors via the `ccat.colors` file.
+- Regex-color mappings are stored in configuration files.
+- Uses the file extension to determine which configuration file to use.
+- Highly extensible - to add a config file for an specific file type, name the file `<extension>.conf`.
+- Support for printing line numbers with the `-n` flag.
+- Statically linked Go binary - no runtime dependencies, config files are distributed along with the binary.
+- Linux and MacOS supported.
+
+---
+
+### Installing
+
+Download the appropriate zip-file from the 'Releases' section. Place the executable in your PATH.
+
+NOTE: The releases are not available on the GitHub repo (which is a mirror of https://gitea.twomorecents.org/Rockingcool/ccat). Obtain the [releases](https://gitea.twomorecents.org/Rockingcool/ccat/releases) from there instead.
+
+---
+
+### Building from source
+
+If you have the `go` command installed, run `make` after cloning the repository.
+
+---
+
+### Supported Languages
+
+The following languages have config files included by default:
+
+- C
+- Go
+
+---
+
+### Getting Started
+The config files are embedded within the binary. They will automatically be installed to the correct location (`~/.config/ccat` on UNIX) when the program is first run.
+
+As written above, if provided a file with extension `.example`, the program will look for the config file named `example.conf`. If such a file doesn't exist, the file is printed out without any highlighting.
+
+For example, if you want to create syntax highlighting for Java, create a file named `java.conf` in your config directory. In this file, include regular-expressions for each of the langauges's keywords, and provide a corresponding color. Use the provided `c.conf` and `go.conf` files as a starting point.
+
+---
+
+### Config Files
+
+The config files are written in YAML. Each line has the following syntax:
+
+`"<regex>": COLOR`
+
+Note that the regex must be enclosed in double quotes, and the color must be capitalized.
+
+---
+
+### Custom Colors
+
+To define a color of your own, create a file named `ccat.colors` in the config directory (mentioned above). The syntax of this file is the following:
+
+`COLOR: <red> <green> <blue>`
+
+Note that the color name must be capitalized (and shouldn't contain spaces). The RGB values must each be from 0 to 255.
+
+---
+
+### TODO:
+- Windows support.
+- Allow users to provide a config file in the command-line, overriding the extension-based config file.

color.go

@@ -2,8 +2,12 @@ package main
 
 import (
 	"fmt"
+	"os"
+	"strconv"
+	"strings"
 
 	colorData "github.com/fatih/color"
+	"gopkg.in/yaml.v2"
 )
 
 // A color represents a possible color, which text can be printed out in.
@@ -14,6 +18,19 @@ type color struct {
 	colorObj *colorData.Color
 }
 
+// A RGB represents a Red, Blue, Green trio of values, along with SGR parameters.
+// Each value is represented as an int. For info on SGR parameters, see:
+// https://en.wikipedia.org/wiki/ANSI_escape_code#Select_Graphic_Rendition_parameters
+// If 'red', 'green' and 'blue' are all -1, then the default terminal color is used.
+// If some (but not all) of them are -1, an error is thrown.
+type RGB struct {
+	sgr1  int
+	red   int
+	blue  int
+	green int
+	sgr2  int
+}
+
 // The following is a list of all possible colors, stored in a map.
 var possibleColors map[string]color = map[string]color{
 	"BLACK":   {"BLACK", colorData.New(colorData.FgBlack)},
@@ -21,13 +38,14 @@ var possibleColors map[string]color = map[string]color{
 	"GREEN":   {"GREEN", colorData.New(colorData.FgGreen)},
 	"YELLOW":  {"YELLOW", colorData.New(colorData.FgYellow)},
 	"BLUE":    {"BLUE", colorData.New(colorData.FgBlue)},
-	"MAGENTA": {"MAGENTA", colorData.New(38, 2, 254, 141, 255)},
+	"MAGENTA": {"MAGENTA", colorData.New(colorData.FgMagenta)},
 	"CYAN":    {"CYAN", colorData.New(colorData.FgCyan)},
 	"WHITE":   {"WHITE", colorData.New(colorData.FgWhite)},
 	"GRAY":    {"GRAY", colorData.New(colorData.FgWhite, colorData.Faint)},
 	// Last three numbers are RGB. Reference https://en.wikipedia.org/wiki/ANSI_escape_code for what the first two numbers mean.
-	"ORANGE": {"ORANGE", colorData.New(38, 2, 255, 153, 28)},
-	"NONE":   {"NONE", colorData.New()},
+//	"ORANGE":   {"ORANGE", colorData.New(38, 2, 255, 153, 28)},
+//	"DARKBLUE": {"DARKBLUE", colorData.New(38, 2, 0, 112, 255)},
+	"NONE":     {"NONE", colorData.New()},
 }
 
 // Apply the given color 'clr' to all units in 'units', within the indices
@@ -52,9 +70,135 @@ func newColor(colorString string) (color, error) {
 // newColorMust is similar to newColor, but prints an error and exits if the given color isn't valid.
 func newColorMust(colorString string) color {
 	if clr, err := newColor(colorString); err != nil {
-		printAndExit(err.Error())
+		printErrAndExit(err.Error())
 		panic(err) // NEVER REACHED
 	} else {
 		return clr
 	}
 }
+
+// isValidColorName returns true if the given string only contains uppercase alphabetic
+// characters.
+func isValidColorName(colorName string) bool {
+	for _, ch := range colorName {
+		if (ch > 'Z' || ch < 'A') && (ch != '_') {
+			return false
+		}
+	}
+	return true
+}
+
+// stringToRGB takes a string representing an RGB five-tuple. It constructs and RGB type and
+// returns it. Any errors encountered are returned. If an error is returned, it is safe to
+// assume that the string doesn't represent an RGB five-tuple.
+func stringToRGB(rgbString string) (*RGB, error) {
+	values := strings.Split(rgbString, " ")
+	// There must be three space-separated strings.
+	if len(values) != 5 {
+		// TODO: Instead of ignoring these errors and returning a generic error (as I do in the
+		// callee), wrap the error returned from this function, inside the error returned by the callee.
+		return nil, fmt.Errorf("Error parsing RGB five-tuple.")
+	}
+	// If any of the strings doesn't represent an integer (or is out of bounds), return an error.
+	// WARNING: LAZY CODE INCOMING
+	var toReturn RGB
+	var err error
+	toReturn.sgr1, err = strconv.Atoi(values[0])
+	if err != nil {
+		return nil, fmt.Errorf("Error parsing SGR1 integer: Invalid value.")
+	}
+	if toReturn.sgr1 < 0 || toReturn.sgr1 > 107 { // Maximum value for SGR values
+		return nil, fmt.Errorf("Error parsing SGR1 integer: Out-of-bounds.")
+	}
+	toReturn.red, err = strconv.Atoi(values[1])
+	if err != nil {
+		return nil, fmt.Errorf("Error parsing RED integer: Invalid value.")
+	}
+	if toReturn.red < -1 || toReturn.red > 255 {
+		return nil, fmt.Errorf("Error parsing RED integer: Out-of-bounds.")
+	}
+	toReturn.blue, err = strconv.Atoi(values[2])
+	if err != nil {
+		return nil, fmt.Errorf("Error parsing BLUE integer: Invalid value.")
+	}
+	if toReturn.blue < -1 || toReturn.blue > 255 {
+		return nil, fmt.Errorf("Error parsing BLUE integer: Out-of-bounds.")
+	}
+	toReturn.green, err = strconv.Atoi(values[3])
+	if err != nil {
+		return nil, fmt.Errorf("Error parsing GREEN integer: Invalid value.")
+	}
+	if toReturn.green < -1 || toReturn.green > 255 {
+		return nil, fmt.Errorf("Error parsing GREEN integer: Out-of-bounds.")
+	}
+	toReturn.sgr2, err = strconv.Atoi(values[4])
+	if err != nil {
+		return nil, fmt.Errorf("Error parsing SGR2 integer: Invalid value.")
+	}
+	if toReturn.sgr2 < 0 || toReturn.sgr2 > 107 {
+		return nil, fmt.Errorf("Error parsing SGR2 integer: Out-of-bounds.")
+	}
+
+	if !(toReturn.red > 0 && toReturn.blue > 0 && toReturn.green > 0) &&
+		!(toReturn.red == -1 && toReturn.green == -1 && toReturn.blue == -1) {
+		return nil, fmt.Errorf("Error parsing color: All values must be positive or -1 for default terminal color.")
+	}
+	return &toReturn, nil
+}
+
+// loadColorsFromFile loads the colors defined in the given config file, and adds them to
+// the possibleColors map. This allows the user to define custom colors at run-time.
+// The colors config file has the following syntax:
+// COLOR: <SGR1> <RED> <GREEN> <BLUE> <SGR2>
+//
+// Note that the color must be capitalized (and not contain spaces), and the R, G and B
+// values must be from -1 to 255 (-1 refers to the default terminal color, and all three values
+// must be -1 for this to work).
+func loadColorsFromFile(filepath string) error {
+	data, err := os.ReadFile(filepath)
+	if err != nil {
+		panic(err)
+	}
+	// Read color config file into a MapSlice
+	tempMapSlice := yaml.MapSlice{}
+	if err := yaml.Unmarshal(data, &tempMapSlice); err != nil {
+		return fmt.Errorf("Unable to read color config file: %s", filepath)
+	}
+
+	for _, item := range tempMapSlice {
+		if !(isValidColorName(item.Key.(string))) {
+			return fmt.Errorf("Invalid color name: %s", item.Key.(string))
+		}
+		var rgb *RGB
+		if rgb, err = stringToRGB(item.Value.(string)); err != nil {
+			return fmt.Errorf("Invalid RGB trio: %s", item.Value.(string))
+		}
+		// If we haven't returned an error yet, the color must be valid.
+		// Add it to the map. colorData.New() expects values of type colorData.Attribute,
+		// so we must cast our RGB values accordingly.
+		// First, check if one of the color values is -1. If it is, they must all be negative (based
+		// on the check in 'stringToRGB()'). If this is the case, don't put the color values.
+		if rgb.red == -1 {
+			possibleColors[item.Key.(string)] = color{
+				item.Key.(string),
+				colorData.New(
+					colorData.Attribute(rgb.sgr2),
+				),
+			}
+		} else {
+			possibleColors[item.Key.(string)] = color{
+				item.Key.(string),
+				colorData.New(
+					colorData.Attribute(rgb.sgr1),
+					2,
+					colorData.Attribute(rgb.red),
+					colorData.Attribute(rgb.blue),
+					colorData.Attribute(rgb.green),
+					colorData.Attribute(rgb.sgr2),
+				),
+			}
+		}
+	}
+
+	return nil
+}

config.go

@@ -1,14 +1,68 @@
 package main
 
 import (
-	"ccat/stack"
+	"embed"
+	"errors"
+	"io/fs"
 	"os"
-	"regexp"
+	"path/filepath"
+	"runtime"
 	"strings"
 
+	"gitea.twomorecents.org/Rockingcool/ccat/stack"
+	"gitea.twomorecents.org/Rockingcool/kleingrep/regex"
+
 	"gopkg.in/yaml.v2"
 )
 
+//go:embed config
+var storedConfigs embed.FS // Embed the folder containing config files
+
+// runningOnWindows: At the moment this function isn't used. When Window support is added,
+// it will be used to determine if the program is being run on Windows.
+func runningOnWindows() bool {
+	return runtime.GOOS == "windows"
+}
+
+// generateDefaultConfigs is used to generate a folder of default config files
+// for common languages. These default config files are embedded into the program, and will
+// be outputted into the given directory.
+//
+// If there is an error encountered, the error is returned.
+func generateDefaultConfigs(configOutputPath string) error {
+	err := os.MkdirAll(configOutputPath, 0755)
+	if err != nil {
+		if os.IsExist(err) {
+			return errors.New("Directory already exists.")
+		} else {
+			return errors.New("Unable to create directory.")
+		}
+	}
+
+	// Copy each folder from the embedded filesystem, into the destination path
+	err = fs.WalkDir(storedConfigs, "config", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() { // Skip directories
+			return nil
+		}
+		relPath, _ := filepath.Rel("config", path)
+		dstPath := filepath.Join(configOutputPath, relPath) // Destination path
+
+		data, err := storedConfigs.ReadFile(path)
+		if err != nil {
+			return err
+		}
+
+		if err := os.WriteFile(dstPath, data, 0644); err != nil {
+			return err
+		}
+		return nil
+	})
+	return nil
+}
+
 // 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
@@ -34,13 +88,13 @@ func loadConfig(configFilename string) (stack.Stack[regColor], error) {
 	//  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))
+		re := regex.MustCompile(item.Key.(string), regex.RE_MULTILINE, regex.RE_SINGLE_LINE)
 		clr, err := newColor(item.Value.(string))
 		if err != nil {
 			return *stack.NewStack[regColor](0), err
 		}
 		// If we got past the errors, then the color _must_ be valid.
-		regColorStack.Push(regColor{re, clr})
+		regColorStack.Push(regColor{&re, clr})
 	}
 
 	return *regColorStack, nil

config/c.conf

@@ -10,11 +10,17 @@
 # Strings in double quotes and single quotes
 '"(.*?)"': BLUE
 "'(.)'": BLUE
+# Text inside angle-brackets (used in 'include' statements)
+'\<(.*?)\>': BLUE
 # Assignments and comparisons
 # TODO: Add less than, greater than, not equal to, and struct pointer member access
-'(?:\s|\b)(=|==|!=|<=|>=|\->)(\s|\b)' : CYAN
+'(?:\s|\b)(=|==|!=|\<=|\>=|\->)(\s|\b)' : CYAN
+
+# Built-in boolean values, modifiers
+'\b(static|const|true|false)\b': DARKBLUE
+
 # Keywords
 '\b(if|else|while|do|for|return)\b': CYAN
-'^(#ifdef|#ifndef|#define|#include)\b': CYAN
+'(\n|^)(#ifdef|#ifndef|#define|#include)\b': CYAN
 # Data Types
 '\b(int|char|float|double|void|long|short|unsigned|signed|bool)\b': YELLOW

config/ccat.colors

@@ -0,0 +1,8 @@
+# The first and last fields are SGR values, used to control things
+# like bold and italic text. If you're unsure what to put, use '38'
+# for the first one and '22' for the last one, for normal text.
+# The last three values are R G B values.
+PINK: 38 244 211 244 22
+BOLD_WHITE: 38 -1 -1 -1 1
+ITALIC_WHITE: 38 -1 -1 -1 3
+UNDERLINE_WHITE: 38 -1 -1 -1 4

config/go.conf

@@ -0,0 +1,28 @@
+# Priority decreases going downward ie. If two regexes match the same piece of
+# text, the one defined earlier will take precedence over the one defined later.
+# Comments
+'//[^\n]*': GRAY
+'/\*[^*]*\*+(?:[^/*][^*]*\*+)*/': GRAY
+# Numbers and special values
+'\b\-?[0-9]*\b': MAGENTA
+'\b(true|false)\b': MAGENTA
+'\b(nil)\b': MAGENTA
+# Strings in double quotes and backticks
+'"(.*?)"': BLUE
+'`(.*?)`': BLUE
+# Bytes / Runes
+"'(.)'": BLUE
+"'\\\\(.)'": BLUE # The escape backslash needs to be escaped as well
+# Assignments and comparisons
+'(?:\s|\b)(=|==|!=|\<=|\>=)(\s|\b)' : CYAN
+'(&&)|(\|\|)': CYAN
+# Keywords
+'\b(if|else|for|range|go|func|return|break|continue)\b': CYAN
+'\b(package|import|var|const|type|struct)\b': CYAN
+# Built-in Functions
+'\b(panic|len)\b': GREEN
+# Data Types
+'\b(bool|byte|rune|string|interface|map|chan)\b': YELLOW
+'\b(u?int)(8|16|32|64)?\b': YELLOW
+'\b(float)(32|64)\b': YELLOW
+'\b(complex)(64|128)\b': YELLOW

config/md.conf

@@ -0,0 +1,19 @@
+# Priority decreases going downward ie. If two regexes match the same piece of
+# text, the one defined earlier will take precedence over the one defined later.
+# Headings
+'^#{1,6}.*?$': MAGENTA
+
+# Link text
+'\[.*?\](?=\(.*?\))': UNDERLINE_WHITE
+
+# Link URL
+'https?://\w+\.\w+.*?(?=\))': RED
+
+# Code blocks
+'```(.|\n)+?```': YELLOW
+
+# Bold text
+'\b__[^_]+?__\b': BOLD_WHITE
+
+# Italic text
+'\b_[^_]+?_\b': ITALIC_WHITE

create_release_builds.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+set -euo pipefail
+
+POSSIBLE_GOOS=( "linux" "darwin" )
+POSSIBLE_GOARCH=( "amd64" "arm64" )
+
+for OS in "${POSSIBLE_GOOS[@]}"; do
+	for ARCH in "${POSSIBLE_GOARCH[@]}"; do
+		FOLDER_NAME="ccat-$OS-$ARCH"
+		mkdir "${FOLDER_NAME}"
+		GOOS=$OS GOARCH=$ARCH go build -o "${FOLDER_NAME}/"
+		zip -r "${FOLDER_NAME}" "${FOLDER_NAME}"
+		rm -r "${FOLDER_NAME}"
+	done
+done
+

errors.go

@@ -5,7 +5,7 @@ import (
 	"os"
 )
 
-func printAndExit(errorStr string) {
+func printErrAndExit(errorStr string) {
 	fmt.Printf("ERROR: %s\n", errorStr)
 	os.Exit(1)
 }

go.mod

@@ -1,11 +1,14 @@
-module ccat
+module gitea.twomorecents.org/Rockingcool/ccat
 
-go 1.22.5
+go 1.23.1
+
+toolchain go1.24.2
 
 require (
-	github.com/fatih/color v1.17.0 // indirect
+	gitea.twomorecents.org/Rockingcool/kleingrep v0.7.0 // indirect
+	github.com/fatih/color v1.18.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
-	golang.org/x/sys v0.18.0 // indirect
+	golang.org/x/sys v0.25.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )

go.sum

@@ -1,7 +1,13 @@
+gitea.twomorecents.org/Rockingcool/kleingrep v0.6.1 h1:eeryIhh2lDMXsu3D1i95IgW2SPte1DaJxlfmiQjrpsE=
+gitea.twomorecents.org/Rockingcool/kleingrep v0.6.1/go.mod h1:8bcYe2hyjNIDM9J2xnyH5veMCAMzVJQR3c0OkatcEPg=
+gitea.twomorecents.org/Rockingcool/kleingrep v0.7.0 h1:owDJjgulFmg9DmgKBtwZMxdf19wM9VbGchMXq7ZlhIM=
+gitea.twomorecents.org/Rockingcool/kleingrep v0.7.0/go.mod h1:8bcYe2hyjNIDM9J2xnyH5veMCAMzVJQR3c0OkatcEPg=
 github.com/BurntSushi/toml v1.4.0 h1:kuoIxZQy2WRRk1pttg9asf+WVv6tWQuBNVmK8+nqPr0=
 github.com/BurntSushi/toml v1.4.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
 github.com/fatih/color v1.17.0 h1:GlRw1BRJxkpqUCBKzKOw098ed57fEsKeNjpTe3cSjK4=
 github.com/fatih/color v1.17.0/go.mod h1:YZ7TlrGPkiz6ku9fK3TLD/pl3CpsiFyu8N92HLgmosI=
+github.com/fatih/color v1.18.0 h1:S8gINlzdQ840/4pfAwic/ZE0djQEH3wM94VfqLTZcOM=
+github.com/fatih/color v1.18.0/go.mod h1:4FelSpRwEGDpQ12mAdzqdOukCy4u8WUtOY6lkT/6HfU=
 github.com/go-yaml/yaml v2.1.0+incompatible h1:RYi2hDdss1u4YE7GwixGzWwVo47T8UQwnTLB6vQiq+o=
 github.com/go-yaml/yaml v2.1.0+incompatible/go.mod h1:w2MrLa16VYP0jy6N7M5kHaCkaLENm+P+Tv+MfurjSw0=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
@@ -13,6 +19,8 @@ golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
 golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.25.0 h1:r+8e+loiHxRqhXVl6ML1nO3l1+oFoWbnlu2Ehimmi34=
+golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

main.go

@@ -1,8 +1,11 @@
 package main
 
 import (
+	"bytes"
 	"errors"
+	"flag"
 	"fmt"
+	"math"
 	"os"
 	"path/filepath"
 )
@@ -15,7 +18,7 @@ func fileExists(filename string) bool {
 	} else if errors.Is(err, os.ErrNotExist) {
 		return false
 	} else {
-		printAndExit(err.Error())
+		printErrAndExit(err.Error())
 		return false // NEVER REACHED
 	}
 }
@@ -24,7 +27,7 @@ func fileExists(filename string) bool {
 // the file doesn't exist.
 func mustExist(filename string) {
 	if fileExists(filename) != true {
-		printAndExit(os.ErrNotExist.Error())
+		printErrAndExit(os.ErrNotExist.Error())
 	}
 }
 
@@ -32,12 +35,12 @@ func mustExist(filename string) {
 // It returns two values: the first is true if the config file exists.
 // If it does, the second value is the config filename.
 // If it doesn't, the second value is blank and can be ignored.
-func getConfig(extension string) (bool, string) {
+func getConfig(configPath, extension string) (bool, string) {
 	if extension == "" {
 		return false, ""
 	}
 	// Assuming the file has an extension
-	fileName := "config/" + extension[1:] + ".conf"
+	fileName := filepath.Join(configPath, extension[1:]+".conf")
 	if exists := fileExists(fileName); exists == false {
 		return false, ""
 	} else {
@@ -52,41 +55,89 @@ func printFile(fileName string) {
 	mustExist(fileName)
 	data, err := os.ReadFile(fileName)
 	if err != nil {
-		printAndExit(err.Error())
+		printErrAndExit(err.Error())
 	}
 	fmt.Print(string(data))
 	return
 }
 
+// computeLineNumDigits computes the number of digits in the number of lines
+// in the given byte array.
+func computeLineNumDigits(data []byte) int {
+	numLines := bytes.Count(data, []byte{'\n'}) + 1
+	return int(math.Round(math.Log10(float64(numLines))))
+}
+
 func main() {
+	disableColorFlag := flag.Bool("d", false, "Disable color")
+	lineNumberFlag := flag.Bool("n", false, "Print line numbers")
+	// Used only if lineNumberFlag is true
+	var lineNumDigits int
+	var lineNum int
+	flag.Parse()
+
+	// Check if config exists. If it doesn't, generate the config files.
+	userHomeDir, err := os.UserHomeDir() // Get current user's home directory, to construct config path
+	if err != nil {
+		panic(err)
+	}
+	configPath := filepath.Join(userHomeDir + "/.config/ccat/")
+	if _, err := os.Stat(configPath); os.IsNotExist(err) {
+		generateDefaultConfigs(configPath)
+	}
 
 	// Check if user has provided a file name
-	if len(os.Args) != 2 {
-		printAndExit("Invalid number of arguments")
+	if len(flag.Args()) < 1 {
+		printErrAndExit("No File specified")
 	}
-	fileName := os.Args[1]
+	fileName := flag.Args()[0]
+
+	// Check if file exists.
 	mustExist(fileName)
 
 	extension := filepath.Ext(fileName)
-	configExists, configFilename := getConfig(extension)
-	// If the given file has no corresponding config, print it out
-	// and exit.
+	configExists, configFilename := getConfig(configPath, extension)
+	// If the given file has no corresponding config, print the file out and exit.
 	if configExists == false {
 		printFile(fileName)
 		return
 	}
+
+	// To save computing time, determine here if the file is empty. If it is, exit
+	// the program.
+	finfo, err := os.Stat(fileName)
+	if err != nil {
+		panic(err)
+	}
+	if finfo.Size() == 0 {
+		os.Exit(0)
+	}
+
+	// Assuming the file is not empty...
+	// If a ccat.colors file exists in the config directory, load all the colors in it
+	if fileExists(filepath.Join(configPath, "ccat.colors")) {
+		err := loadColorsFromFile(filepath.Join(configPath, "ccat.colors"))
+		if err != nil {
+			printErrAndExit(err.Error())
+		}
+	}
 	// If the given file has a config, load the config into a stack of regColors.
 	regColorStack, err := loadConfig(configFilename)
 	if err != nil {
-		printAndExit(err.Error())
+		printErrAndExit(err.Error())
 	}
 
 	// Load the input file into a colorunit slice (units) and a byte slice (data)
 	units, data, err := loadInputFile(fileName)
 	if err != nil {
-		printAndExit(err.Error())
+		printErrAndExit(err.Error())
 	}
 
+	// If the '-n' flag is set, compute the number of digits in the number of lines
+	// in the file, to determine the padding for the line numbers.
+	if *lineNumberFlag {
+		lineNumDigits = computeLineNumDigits(data)
+	}
 	// For each regular expression in the stack, apply it to the byte slice. Find
 	// the first and last index of all matches of the regex. Then apply the corresponding color
 	// to every character within these indices.
@@ -94,7 +145,9 @@ func main() {
 	// The infinite for loop exists, because I couldn't figure out a way to pop an element from
 	// the stack inside the 'for' statement. The loop exits when the 'pop' call returns 'false',
 	// indicating that the stack is empty.
-	for {
+	//
+	// The loop is also only run if the 'disable color' flag is not set.
+	for *disableColorFlag == false {
 		regclr, ok := regColorStack.Pop()
 		// regColorStack.Pop() returns false when there are no more elements to pop
 		if ok != true {
@@ -104,18 +157,32 @@ func main() {
 		clr := regclr.clr
 		// Returns an int double-slice, where each slice contains the start and end indices
 		// of the match. In this case, I am finding all the matches of 're' in 'data'.
-		matches := re.FindAllSubmatchIndex(data, -1)
+		matches := re.FindAllSubmatch(string(data))
 		if matches == nil {
 			continue
 		}
 		// For each match, apply the corresponding color to all characters in the match.
 		for _, match := range matches {
-			units = applyColor(units, match[0], match[1], clr)
+			units = applyColor(units, match[0].StartIdx, match[0].EndIdx, clr)
 		}
 	}
 
 	// After all possible regexes have been matched, print out the contents of 'units'.
-	for _, unit := range units {
+
+	// If the line number flag is set, initialize the lineNum variable and print the first line number
+	// with the appropriate padding.
+	if *lineNumberFlag {
+		lineNum = 1
+		fmt.Printf("   %*d  ", lineNumDigits, lineNum)
+		lineNum++
+	}
+	for idx, unit := range units {
 		unit.print()
+		// If the flag is set and we encounter a newline (and the newline isn't a trailing newline),
+		// then print the next line number.
+		if *lineNumberFlag && unit.ch == '\n' && idx != len(units)-1 {
+			fmt.Printf("   %*d  ", lineNumDigits, lineNum)
+			lineNum++
+		}
 	}
 }

regcolor.go

@@ -1,10 +1,10 @@
 package main
 
-import "regexp"
+import "gitea.twomorecents.org/Rockingcool/kleingrep/regex"
 
 // A regColor is a regex-color pair. The config file is read
 // into a stack of this data type.
 type regColor struct {
-	re  *regexp.Regexp
+	re  *regex.Reg
 	clr color
 }

test.c

@@ -1,173 +0,0 @@
-//go:build exclude
-#include "easysock.h"
-
-
-int create_socket(int network, char transport) {
-	int domain;
-	int type;
-
-	if (network == 4) {
-		domain = AF_INET;
-	} else if (network == 6) {
-		domain = AF_INET6;
-	} else {
-		return -1;
-	}
-
-	if (transport == 'T') {
-		type = SOCK_STREAM;
-	} else if (transport == 'U') {
-		type = SOCK_DGRAM;
-	} else {
-		return -1;
-	}
-
-	int newSock = socket(domain,type,0);
-	return newSock;
-}
-
-
-int create_addr(int network, char* address, int port,struct sockaddr* dest) {
-	if (network == 4) {
-		struct sockaddr_in listen_address;
-
-		listen_address.sin_family = AF_INET;
-		listen_address.sin_port = htons(port);
-		inet_pton(AF_INET,address,&listen_address.sin_addr);
-		memcpy(dest,&listen_address,sizeof(listen_address));
-		return 0;
-
-	} else if (network == 6) {
-		struct sockaddr_in6 listen_ipv6;
-		listen_ipv6.sin6_family = AF_INET6;
-		listen_ipv6.sin6_port = htons(port);
-		inet_pton(AF_INET6,address,&listen_ipv6.sin6_addr);
-		memcpy(dest,&listen_ipv6,sizeof(listen_ipv6));
-		return 0;
-
-	} else {
-		return -202;
-	}
-
-
-
-}
-
-int create_local (int network, char transport, char* address, int port,struct sockaddr* addr_struct) {
-	int socket = create_socket(network,transport);
-	if (socket < 0) {
-		return (-1 * errno);
-	}
-	create_addr(network,address,port,addr_struct);
-	int addrlen;
-	if (network == 4) {
-		addrlen = sizeof(struct sockaddr_in);
-	} else if (network == 6) {
-		addrlen = sizeof(struct sockaddr_in6);
-	} else {
-		return -202;
-	}
-
-	/* The value of addrlen should be the size of the 'sockaddr'.
-	This should be set to the size of 'sockaddr_in' for IPv4, and 'sockaddr_in6' for IPv6.
-	See https://stackoverflow.com/questions/73707162/socket-bind-failed-with-invalid-argument-error-for-program-running-on-macos */
-
-	int i = bind (socket,addr_struct,(socklen_t)addrlen);
-	if (i < 0) {
-		return (-1 * errno);
-	}
-	return socket;
-}
-
-int create_remote (int network,char transport,char* address,int port,struct sockaddr* remote_addr_struct) {
-
-	struct addrinfo hints;  /* Used to tell getaddrinfo what kind of address we want */
-	struct addrinfo* results; /* Used by getaddrinfo to store the addresses */
-
-
-	if (check_ip_ver(address) < 0) { /* If the address is a domain name */
-		int err_code;
-		char* port_str = malloc(10 * sizeof(char));
-
-		sprintf(port_str,"%d",port); /* getaddrinfo expects a string for its port */
-
-
-		memset(&hints,'\0',sizeof(hints));
-		hints.ai_socktype = char_to_socktype(transport);
-
-		err_code = getaddrinfo(address,port_str,&hints,&results);
-		if (err_code != 0) {
-			return (-1 * err_code);
-		}
-		remote_addr_struct = results->ai_addr;
-		network = inet_to_int(results->ai_family);
-	} else {
-	        create_addr(network,address,port,remote_addr_struct);
-	}
-
-	int socket = create_socket(network,transport);
-	if (socket < 0) {
-                return (-1 * errno);
-        }
-
-       	int addrlen;
-	if (network == 4) {
-		addrlen = sizeof(struct sockaddr_in);
-	} else if (network == 6) {
-		addrlen = sizeof(struct sockaddr_in6);
-	} else {
-		return (-202);
-	}
-
-	/* The value of addrlen should be the size of the 'sockaddr'.
-	This should be set to the size of 'sockaddr_in' for IPv4, and 'sockaddr_in6' for IPv6.
-	See https://stackoverflow.com/questions/73707162/socket-bind-failed-with-invalid-argument-error-for-program-running-on-macos */
-
-        int i = connect(socket,remote_addr_struct,(socklen_t)addrlen);
-	if (i < 0) {
-		return (-1 * errno);
-	}
-        return socket;
-}
-
-
-int check_ip_ver(char* address) {
-	char buffer[16]; /* 16 chars - 128 bits - is enough to hold an ipv6 address */
-	if (inet_pton(AF_INET,address,buffer) == 1) {
-		return 4;
-	} else if (inet_pton(AF_INET6,address,buffer) == 1) {
-		return 6;
-	} else {
-		return -1;
-	}
-}
-
-int int_to_inet(int network) {
-	if (network == 4) {
-		return AF_INET;
-	} else if (network == 6) {
-		return AF_INET6;
-	} else {
-		return -202;
-	}
-}
-
-int inet_to_int(int af_type) {
-	if (af_type == AF_INET) {
-		return 4;
-	} else if (af_type == AF_INET6) {
-		return 6;
-	} else {
-		return -207;
-	}
-}
-
-int char_to_socktype(char transport) {
-	if (transport == 'T') {
-		return SOCK_STREAM;
-	} else if (transport == 'U') {
-		return SOCK_DGRAM;
-	} else {
-		return -250;
-	}
-}