Allow fallback in case of out of bound

Cargo.toml

@@ -22,7 +22,8 @@ regex = { version = "1.10", default-features = false, features = ["std", "unicod
 serde_json = "1.0.113"
 
 [features]
-default = ["regex"]
+default = ["regex", "fast-lane"]
+fast-lane = []
 
 [dev-dependencies]
 assert_cmd = "2.0.13"

README.md

@@ -53,7 +53,8 @@ FLAGS:
 
 OPTIONS:
     -f, --fields <bounds>         Fields to keep, 1-indexed, comma separated.
-                                  Use colon to include everything in a range.
+                                  Use colon (:) to match a range (inclusive).
+                                  Use equal (=) to apply out of bound fallback.
                                   Fields can be negative (-1 is the last field).
                                   [default 1:]
 
@@ -64,6 +65,7 @@ OPTIONS:
                                     -f 3,2   => cb
                                     -f 3,1:2 => ca-b
                                     -f -3:-2 => b-c
+                                    -f 1,8=fallback => afallback
 
                                   To re-apply the delimiter add -j, to replace
                                   it add -r (followed by the new delimiter).
@@ -84,6 +86,10 @@ OPTIONS:
     -r, --replace-delimiter <new> Replace the delimiter with the provided text
     -t, --trim <type>             Trim the delimiter (greedy). Valid values are
                                   (l|L)eft, (r|R)ight, (b|B)oth
+        --fallback-oob <fallback> Generic fallback output for any field that
+                                  cannot be found (oob stands for out of bound).
+                                  It's overridden by any fallback assigned to a
+                                  specific field (see -f for help)
 
 Options precedence:
     --trim and --compress-delimiter are applied before --fields or similar

doc/tuc.1

@@ -67,7 +67,11 @@ Print fields as a JSON array of strings
 .PD 0
 .P
 .PD
-\ \ \ \ \ \ \ Use colon to include everything in a range.
+\ \ \ \ \ \ \ Use colon (:) to match a range (inclusive).
+.PD 0
+.P
+.PD
+\ \ \ \ \ \ \ Use equal (=) to apply out of bound fallback.
 .PD 0
 .P
 .PD
@@ -100,6 +104,10 @@ Print fields as a JSON array of strings
 .P
 .PD
 \ \ \ \ \ \ \ \ \ \f[V]-f -3:-2 => b-c\f[R]
+.PD 0
+.P
+.PD
+\ \ \ \ \ \ \ \ \ \f[V]-f 1,8=fallback => afallback\f[R]
 .PP
 \ \ \ \ \ \ \ To re-apply the delimiter add -j, to replace
 .PD 0
@@ -173,6 +181,24 @@ To merge lines, use --no-join
 .P
 .PD
 \ \ \ \ \ \ \ Valid values are (l|L)eft, (r|R)ight, (b|B)oth
+.PP
+\ \ \ \ \f[B]--fallback-oob\f[R] [fallback]
+.PD 0
+.P
+.PD
+\ \ \ \ \ \ \ Generic fallback output for any field that
+.PD 0
+.P
+.PD
+\ \ \ \ \ \ \ cannot be found (oob stands for out of bound).
+.PD 0
+.P
+.PD
+\ \ \ \ \ \ \ It\[cq]s overridden by any fallback assigned to a
+.PD 0
+.P
+.PD
+\ \ \ \ \ \ \ specific field (see -f for help)
 .SH OPTIONS PRECEDENCE
 .PP
 --trim and --compress-delimiter are applied before --fields or similar
@@ -181,15 +207,25 @@ To merge lines, use --no-join
 --characters and --fields read and allocate memory one line at a time
 .PP
 --lines allocate memory one line at a time as long as the requested
-fields are ordered and non-negative (e.g.\ -l 1,3:4,4,7), otherwise it
-allocates the whole input in memory (it also happens when -p or -m are
-being used)
+fields are
+.PD 0
+.P
+.PD
+ordered and non-negative (e.g.\ -l 1,3:4,4,7), otherwise it allocates
+.PD 0
+.P
+.PD
+the whole input in memory (it also happens when -p or -m are being used)
 .PP
 --bytes allocate the whole input in memory
 .SH COLORS
 .PP
 Help is displayed using colors.
-Colors will be suppressed in the following circumstances:
+Colors will be suppressed in the
+.PD 0
+.P
+.PD
+following circumstances:
 .IP \[bu] 2
 when the TERM environment variable is not set or set to \[lq]dumb\[rq]
 .IP \[bu] 2

doc/tuc.1.md

@@ -54,7 +54,8 @@ OPTIONS
 
 | **-f**, **\--fields** [bounds]
 |        Fields to keep, 1-indexed, comma separated.
-|        Use colon to include everything in a range.
+|        Use colon (:) to match a range (inclusive).
+|        Use equal (=) to apply out of bound fallback.
 |        Fields can be negative (-1 is the last field).
 
 |        [default 1:]
@@ -66,6 +67,7 @@ OPTIONS
 |          `-f 3,2   => cb`
 |          `-f 3,1:2 => ca-b`
 |          `-f -3:-2 => b-c`
+|          `-f 1,8=fallback => afallback`
 
 |        To re-apply the delimiter add -j, to replace
 |        it add -r (followed by the new delimiter)
@@ -100,6 +102,12 @@ OPTIONS
 |        Trim the delimiter (greedy).
 |        Valid values are (l|L)eft, (r|R)ight, (b|B)oth
 
+|     **\--fallback-oob** [fallback]
+|        Generic fallback output for any field that
+|        cannot be found (oob stands for out of bound).
+|        It's overridden by any fallback assigned to a
+|        specific field (see -f for help)
+
 OPTIONS PRECEDENCE
 ==================
 
@@ -110,17 +118,17 @@ MEMORY CONSUMPTION
 
 \--characters and \--fields read and allocate memory one line at a time
 
-\--lines allocate memory one line at a time as long as the requested fields are
- ordered and non-negative (e.g. -l 1,3:4,4,7), otherwise it allocates
- the whole input in memory (it also happens when -p or -m are being used)  
+| \--lines allocate memory one line at a time as long as the requested fields are
+| ordered and non-negative (e.g. -l 1,3:4,4,7), otherwise it allocates
+| the whole input in memory (it also happens when -p or -m are being used)
 
 \--bytes allocate the whole input in memory
 
 COLORS
 ======
 
-Help is displayed using colors. Colors will be suppressed in the
-following circumstances:
+| Help is displayed using colors. Colors will be suppressed in the
+| following circumstances:
 
 - when the TERM environment variable is not set or set to "dumb"
 - when the NO_COLOR environment variable is set (regardless of value)

src/bin/tuc.rs

@@ -7,16 +7,41 @@ use tuc::bounds::{BoundOrFiller, BoundsType, UserBoundsList};
 use tuc::cut_bytes::read_and_cut_bytes;
 use tuc::cut_lines::read_and_cut_lines;
 use tuc::cut_str::read_and_cut_str;
-use tuc::fast_lane::{read_and_cut_text_as_bytes, FastOpt};
 use tuc::help::{get_help, get_short_help};
 use tuc::options::{Opt, EOL};
 
+#[cfg(feature = "fast-lane")]
+use tuc::fast_lane::{read_and_cut_text_as_bytes, FastOpt};
+
 #[cfg(feature = "regex")]
 use tuc::options::RegexBag;
 
 #[cfg(feature = "regex")]
 use regex::bytes::Regex;
 
+#[cfg(not(feature = "fast-lane"))]
+struct FastOpt {}
+
+#[cfg(not(feature = "fast-lane"))]
+impl<'a> TryFrom<&'a Opt> for FastOpt {
+    type Error = &'static str;
+
+    fn try_from(_value: &'a Opt) -> Result<Self, Self::Error> {
+        Err("This binary was not compiled with the feature fast-lane")
+    }
+}
+
+#[cfg(not(feature = "fast-lane"))]
+fn read_and_cut_text_as_bytes<R: std::io::BufRead, W: Write>(
+    _stdin: &mut R,
+    _stdout: &mut W,
+    _fast_opt: &FastOpt,
+) -> Result<()> {
+    Err(anyhow::Error::msg(
+        "This binary was not compiled with the feature fast-lane",
+    ))
+}
+
 fn parse_args() -> Result<Opt, pico_args::Error> {
     let mut pargs = pico_args::Arguments::from_env();
 
@@ -185,6 +210,18 @@ fn parse_args() -> Result<Opt, pico_args::Error> {
         bounds,
         replace_delimiter,
         trim: pargs.opt_value_from_str(["-t", "--trim"])?,
+        fallback_oob: pargs
+            .opt_value_from_str("--fallback-oob")
+            .or_else(|e| match e {
+                pico_args::Error::OptionWithoutAValue(_) => {
+                    // We must consume the arg ourselves (it's not done on error)
+                    pargs.contains("--fallback-oob=");
+
+                    Ok(Some("".into()))
+                }
+                _ => Err(e),
+            })?
+            .map(|x: String| x.into()),
         regex_bag,
     };