diff options
| -rw-r--r-- | tvix/eval/src/builtins/mod.rs | 29 | ||||
| -rw-r--r-- | tvix/eval/src/errors.rs | 13 | ||||
| -rw-r--r-- | tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.exp | 1 | ||||
| -rw-r--r-- | tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.nix | 18 |
4 files changed, 61 insertions, 0 deletions
diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs index aeffca49950d..4bcaaf7a00e5 100644 --- a/tvix/eval/src/builtins/mod.rs +++ b/tvix/eval/src/builtins/mod.rs @@ -4,6 +4,7 @@ //! available builtins in Nix. use std::{ + cmp, collections::{BTreeMap, HashMap}, path::PathBuf, rc::Rc, @@ -192,6 +193,34 @@ fn pure_builtins() -> Vec<Builtin> { let a = args.pop().unwrap(); arithmetic_op!(a, b, -) }), + Builtin::new("substring", 3, |args, vm| { + let beg = args[0].force(vm)?.as_int()?; + let len = args[1].force(vm)?.as_int()?; + let x = args[2].force(vm)?.to_str()?; + + if beg < 0 { + return Err(ErrorKind::IndexOutOfBounds { index: beg }); + } + let beg = beg as usize; + + // Nix doesn't assert that the length argument is + // non-negative when the starting index is GTE the + // string's length. + if beg >= x.as_str().len() { + return Ok(Value::String("".into())); + } + + if len < 0 { + return Err(ErrorKind::NegativeLength { length: len }); + } + + let len = len as usize; + let end = cmp::min(beg + len, x.as_str().len()); + + Ok(Value::String( + x.as_str()[(beg as usize)..(end as usize)].into(), + )) + }), Builtin::new("throw", 1, |mut args, _| { return Err(ErrorKind::Throw( args.pop().unwrap().to_str()?.as_str().to_owned(), diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs index 1b8f58356cab..6331ee64be1c 100644 --- a/tvix/eval/src/errors.rs +++ b/tvix/eval/src/errors.rs @@ -80,6 +80,11 @@ pub enum ErrorKind { /// An error occurred when parsing an integer ParseIntError(ParseIntError), + /// A negative integer was used as a value representing length. + NegativeLength { + length: i64, + }, + /// Tvix internal warning for features triggered by users that are /// not actually implemented yet, and without which eval can not /// proceed. @@ -213,6 +218,13 @@ to a missing value in the attribute set(s) included via `with`."#, format!("invalid integer: {}", err) } + ErrorKind::NegativeLength { length } => { + format!( + "cannot use a negative integer, {}, for a value representing length", + length + ) + } + ErrorKind::NotImplemented(feature) => { format!("feature not yet implemented in Tvix: {}", feature) } @@ -244,6 +256,7 @@ to a missing value in the attribute set(s) included via `with`."#, ErrorKind::IndexOutOfBounds { .. } => "E019", ErrorKind::NotAnAbsolutePath(_) => "E020", ErrorKind::ParseIntError(_) => "E021", + ErrorKind::NegativeLength { .. } => "E022", ErrorKind::NotImplemented(_) => "E999", } } diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.exp new file mode 100644 index 000000000000..168276022898 --- /dev/null +++ b/tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.exp @@ -0,0 +1 @@ +[ "tes" "testing" "" "estin" "ting" "" "" "" "" "est" "est" "est" "est" "est" "est" "" ] diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.nix new file mode 100644 index 000000000000..f4ee82e2736f --- /dev/null +++ b/tvix/eval/src/tests/tvix_tests/eval-okay-builtins-substring.nix @@ -0,0 +1,18 @@ +[ + (builtins.substring 0 3 "testing") + (builtins.substring 0 300 "testing") + (builtins.substring 3 0 "testing") + (builtins.substring 1 5 "testing") + (builtins.substring 3 5 "testing") + (builtins.substring 300 300 "testing") + (builtins.substring 301 300 "testing") + (builtins.substring 0 0 "") + (builtins.substring 0 1 "") + (builtins.substring (builtins.add 0 1) 3 "testing") + (builtins.substring 1 (builtins.add 3 0) "testing") + (builtins.substring (builtins.add 0 1) (builtins.add 3 0) "testing") + (builtins.substring (builtins.add 0 1) (builtins.add 3 0) "testing") + (builtins.substring (builtins.add 0 1) (builtins.add 3 0) ("test" + "ing")) + (builtins.substring (builtins.add 0 1) (builtins.add 3 0) ("test" + "ing")) + (builtins.substring 300 (-10) "testing") +] |