fix #32: treat header filters case insensitively

cfg/config.go

@@ -287,7 +287,7 @@ func (conf *Config) PrepareFilters() error {
 				parts[0], err)
 		}
 
-		conf.Filters[strings.ToLower(parts[0])] = reg
+		conf.Filters[strings.ToLower(strings.ToLower(parts[0]))] = reg
 	}
 
 	return nil

cmd/tablizer.go

@@ -188,6 +188,11 @@ DESCRIPTION
 
     where "C" is our regexp which matches CMD.
 
+    If a column specifier doesn't look like a regular expression, matching
+    against header fields will be case insensitive. So, if you have a field
+    with the name "ID" then these will all match: "-c id", "-c Id". The same
+    rule applies to the options "-T" and "-F".
+
   TRANSPOSE FIELDS USING REGEXPS
     You can manipulate field contents using regular expressions. You have to
     tell tablizer which field[s] to operate on using the option "-T" and the
@@ -203,6 +208,24 @@ DESCRIPTION
 
         |search-regexp|replace-string|
 
+    Example:
+
+        cat t/testtable2
+        NAME  DURATION
+        x     10
+        a     100
+        z     0
+        u     4
+        k     6
+    
+        cat t/testtable2 | tablizer -T2 -R '/^\d/4/' -n
+        NAME    DURATION 
+        x       40      
+        a       400     
+        z       4       
+        u       4       
+        k       4
+
   OUTPUT MODES
     There might be cases when the tabular output of a program is way too
     large for your current terminal but you still need to see every column.

lib/helpers.go

@@ -106,24 +106,33 @@ func PrepareColumnVars(columns string, data *Tabdata) ([]int, error) {
 
 	usecolumns := []int{}
 
-	for _, use := range strings.Split(columns, ",") {
-		if len(use) == 0 {
+	isregex := regexp.MustCompile(`\W`)
+
+	for _, columnpattern := range strings.Split(columns, ",") {
+		if len(columnpattern) == 0 {
 			return nil, fmt.Errorf("could not parse columns list %s: empty column", columns)
 		}
 
-		usenum, err := strconv.Atoi(use)
+		usenum, err := strconv.Atoi(columnpattern)
 		if err != nil {
-			// might be a regexp
-			colPattern, err := regexp.Compile(use)
+			// not a number
+
+			if !isregex.MatchString(columnpattern) {
+				// is not a regexp (contains no non-word chars)
+				// lc() it so that word searches are case insensitive
+				columnpattern = strings.ToLower(columnpattern)
+			}
+
+			colPattern, err := regexp.Compile(columnpattern)
 			if err != nil {
 				msg := fmt.Sprintf("Could not parse columns list %s: %v", columns, err)
 
 				return nil, errors.New(msg)
 			}
 
-			// find matching header fields
+			// find matching header fields, ignoring case
 			for i, head := range data.headers {
-				if colPattern.MatchString(head) {
+				if colPattern.MatchString(strings.ToLower(head)) {
 					usecolumns = append(usecolumns, i+1)
 				}
 			}

lib/parser.go

@@ -120,9 +120,6 @@ func parseTabular(conf cfg.Config, input io.Reader) (Tabdata, error) {
 		if !hadFirst {
 			// header processing
 			data.columns = len(parts)
-			// if Debug {
-			// 	fmt.Println(parts)
-			// }
 
 			// process all header fields
 			for _, part := range parts {

tablizer.1

@@ -133,7 +133,7 @@
 .\" ========================================================================
 .\"
 .IX Title "TABLIZER 1"
-.TH TABLIZER 1 "2025-01-13" "1" "User Commands"
+.TH TABLIZER 1 "2025-01-14" "1" "User Commands"
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -351,6 +351,11 @@ We want to see only the \s-1CMD\s0 column and use a regex for this:
 .Ve
 .PP
 where \*(L"C\*(R" is our regexp which matches \s-1CMD.\s0
+.PP
+If a column specifier doesn't look like a regular expression, matching
+against header  fields will  be case  insensitive. So,  if you  have a
+field with  the name \f(CW\*(C`ID\*(C'\fR then  these will all match:  \f(CW\*(C`\-c id\*(C'\fR, \f(CW\*(C`\-c
+Id\*(C'\fR. The same rule applies to the options \f(CW\*(C`\-T\*(C'\fR and \f(CW\*(C`\-F\*(C'\fR.
 .SS "\s-1TRANSPOSE FIELDS USING REGEXPS\s0"
 .IX Subsection "TRANSPOSE FIELDS USING REGEXPS"
 You can manipulate field contents using regular expressions. You have
@@ -370,6 +375,26 @@ use a regexp containing the \f(CW\*(C`/\*(C'\fR character, eg:
 .Vb 1
 \&    |search\-regexp|replace\-string|
 .Ve
+.PP
+Example:
+.PP
+.Vb 7
+\&    cat t/testtable2
+\&    NAME  DURATION
+\&    x     10
+\&    a     100
+\&    z     0
+\&    u     4
+\&    k     6
+\&    
+\&    cat t/testtable2 | tablizer \-T2 \-R \*(Aq/^\ed/4/\*(Aq \-n
+\&    NAME    DURATION 
+\&    x       40      
+\&    a       400     
+\&    z       4       
+\&    u       4       
+\&    k       4
+.Ve
 .SS "\s-1OUTPUT MODES\s0"
 .IX Subsection "OUTPUT MODES"
 There might be cases  when the tabular output of a  program is way too

tablizer.pod

@@ -206,6 +206,12 @@ We want to see only the CMD column and use a regex for this:
 
 where "C" is our regexp which matches CMD.
 
+If a column specifier doesn't look like a regular expression, matching
+against header  fields will  be case  insensitive. So,  if you  have a
+field with  the name C<ID> then  these will all match:  C<-c id>, C<-c
+Id>. The same rule applies to the options C<-T> and C<-F>.
+
+
 =head2 TRANSPOSE FIELDS USING REGEXPS
 
 You can manipulate field contents using regular expressions. You have