check pattern on startup

TODO.md

@@ -4,7 +4,7 @@
 
 - rm printYamlData() log.Fatal(), maybe return error on all printers?
 
-- refactor parser, there's some duplicate code
+- refactor parser, there's some duplicate code, remove pattern from parser args
 
 ## Features to be implemented
 
@@ -14,6 +14,4 @@
 
 - add --no-headers option
 
--  add input  parsing support  for CSV  including unquoting  of stuff
-  like: `"xxx","1919 b"` etc, maybe an extra option for unquoting
 

cfg/config.go

@@ -17,9 +17,11 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 package cfg
 
 import (
+	"errors"
 	"fmt"
 	"github.com/gookit/color"
 	"os"
+	"regexp"
 )
 
 const DefaultSeparator string = `(\s\s+|\t)`
@@ -36,6 +38,7 @@ type Config struct {
 	OutputMode  int
 	InvertMatch bool
 	Pattern     string
+	PatternR    *regexp.Regexp
 
 	SortMode       string
 	SortDescending bool
@@ -163,3 +166,15 @@ func (c *Config) ApplyDefaults() {
 		c.NoNumbering = true
 	}
 }
+
+func (c *Config) PreparePattern() error {
+	PatternR, err := regexp.Compile(c.Pattern)
+
+	if err != nil {
+		return errors.Unwrap(fmt.Errorf("Regexp pattern %s is invalid: %w", c.Pattern, err))
+	}
+
+	c.PatternR = PatternR
+
+	return nil
+}

cmd/root.go

@@ -73,6 +73,11 @@ func Execute() {
 			conf.CheckEnv()
 			conf.PrepareModeFlags(modeflag)
 			conf.PrepareSortFlags(sortmode)
+
+			if err := conf.PreparePattern(); err != nil {
+				return err
+			}
+
 			conf.ApplyDefaults()
 
 			// actual execution starts here

lib/parser.go

@@ -21,6 +21,7 @@ import (
 	"bufio"
 	"encoding/csv"
 	"errors"
+	"fmt"
 	"github.com/alecthomas/repr"
 	"github.com/tlinden/tablizer/cfg"
 	"io"