Fixes to limit --command-name count appear exactly once or same count with parameters.

src/hyperfine/error.rs

@@ -12,6 +12,7 @@ pub enum ParameterScanError {
     TooLarge,
     ZeroStep,
     StepRequired,
+    DifferentCommandNameCountWithParameters(usize, usize),
 }
 
 impl From<num::ParseIntError> for ParameterScanError {
@@ -40,6 +41,13 @@ impl fmt::Display for ParameterScanError {
                  floating point numbers. The step size can be specified \
                  with the '--parameter-step-size' parameter"
             ),
+            ParameterScanError::DifferentCommandNameCountWithParameters(real, expected) => {
+                write!(
+                    f,
+                    "Current --command-name count is {}: expected {} as parameters",
+                    real, expected
+                )
+            }
         }
     }
 }
@@ -51,6 +59,7 @@ pub enum OptionsError<'a> {
     RunsBelowTwo,
     EmptyRunsRange,
     TooManyCommandNames(usize),
+    DifferentCommandNameCountWithParameters(usize, usize),
     NumericParsingError(&'a str, ParseIntError),
 }
 
@@ -62,6 +71,13 @@ impl<'a> fmt::Display for OptionsError<'a> {
             OptionsError::TooManyCommandNames(n) => {
                 write!(f, "Too many --command-name options: expected {} at most", n)
             }
+            OptionsError::DifferentCommandNameCountWithParameters(real, expected) => {
+                write!(
+                    f,
+                    "Current --command-name count is {}: expected {} as parameters",
+                    real, expected
+                )
+            }
             OptionsError::NumericParsingError(cmd, ref err) => write!(
                 f,
                 "Could not read numeric argument to '--{cmd}': {err}",

src/hyperfine/parameter_range.rs

@@ -2,6 +2,7 @@ use crate::hyperfine::error::ParameterScanError;
 use crate::hyperfine::types::{Command, NumericType, ParameterValue};
 use clap::Values;
 use rust_decimal::Decimal;
+use std::convert::TryInto;
 use std::ops::{Add, AddAssign, Div, Sub};
 use std::str::FromStr;
 
@@ -45,6 +46,22 @@ impl<T: Numeric> RangeStep<T> {
             step,
         }
     }
+
+    fn validate(&self) -> Result<(), ParameterScanError> {
+        if self.end < self.state {
+            return Err(ParameterScanError::EmptyRange);
+        }
+
+        if self.step == T::from(0) {
+            return Err(ParameterScanError::ZeroStep);
+        }
+
+        const MAX_PARAMETERS: usize = 100_000;
+        match self.size_hint() {
+            (_, Some(size)) if size <= MAX_PARAMETERS => Ok(()),
+            _ => Err(ParameterScanError::TooLarge),
+        }
+    }
 }
 
 impl<T: Numeric> Iterator for RangeStep<T> {
@@ -59,24 +76,18 @@ impl<T: Numeric> Iterator for RangeStep<T> {
 
         Some(return_val)
     }
-}
 
-fn validate_params<T: Numeric>(start: T, end: T, step: T) -> Result<(), ParameterScanError> {
+    fn size_hint(&self) -> (usize, Option<usize>) {
-    if end < start {
+        if self.step == T::from(0) {
-        return Err(ParameterScanError::EmptyRange);
+            return (usize::MAX, None);
+        }
+
+        let steps = (self.end - self.state + T::from(1)) / self.step;
+        steps
+            .into()
+            .try_into()
+            .map_or((usize::MAX, None), |u| (u, Some(u)))
     }
-
-    if step == T::from(0) {
-        return Err(ParameterScanError::ZeroStep);
-    }
-
-    const MAX_PARAMETERS: i32 = 100_000;
-    let steps = (end - start + T::from(1)) / step;
-    if steps > T::from(MAX_PARAMETERS) {
-        return Err(ParameterScanError::TooLarge);
-    }
-
-    Ok(())
 }
 
 fn build_parameterized_commands<'a, T: Numeric>(
@@ -87,27 +98,33 @@ fn build_parameterized_commands<'a, T: Numeric>(
     command_strings: Vec<&'a str>,
     param_name: &'a str,
 ) -> Result<Vec<Command<'a>>, ParameterScanError> {
-    validate_params(param_min, param_max, step)?;
     let param_range = RangeStep::new(param_min, param_max, step);
-    let mut commands = vec![];
+    param_range.validate()?;
+    let param_count = param_range.size_hint().1.unwrap();
+    let command_name_count = command_names.len();
+
+    // `--command-name` should appear exactly once or same count with parameters.
+    if command_name_count > 1 && command_name_count != param_count {
+        return Err(ParameterScanError::DifferentCommandNameCountWithParameters(
+            command_name_count,
+            param_count,
+        ));
+    }
 
     let mut i = 0;
-    let name_count = command_names.len();
+    let mut commands = vec![];
     for value in param_range {
         for cmd in &command_strings {
-            // Sets the command name by index (remainder) if exists.
+            let name = command_names
-            let name = if name_count > 0 {
+                .get(i)
-                Some(command_names[i % name_count])
+                .or_else(|| command_names.get(0))
-            } else {
+                .map(|s| *s);
-                None
-            };
-            i += 1;
-
             commands.push(Command::new_parametrized(
                 name,
                 cmd,
                 vec![(param_name, ParameterValue::Numeric(value.into()))],
             ));
+            i += 1;
         }
     }
     Ok(commands)
@@ -182,6 +199,37 @@ fn test_decimal_range() {
     assert_eq!(param_range[10], Decimal::from(1));
 }
 
+#[test]
+fn test_range_step_validate() {
+    let range_step = RangeStep::new(0, 10, 3);
+    assert!(range_step.validate().is_ok());
+
+    let range_step = RangeStep::new(
+        Decimal::from(0),
+        Decimal::from(1),
+        Decimal::from_str("0.1").unwrap(),
+    );
+    assert!(range_step.validate().is_ok());
+
+    let range_step = RangeStep::new(11, 10, 1);
+    assert_eq!(
+        format!("{}", range_step.validate().unwrap_err()),
+        "Empty parameter range"
+    );
+
+    let range_step = RangeStep::new(0, 10, 0);
+    assert_eq!(
+        format!("{}", range_step.validate().unwrap_err()),
+        "Zero is not a valid parameter step"
+    );
+
+    let range_step = RangeStep::new(0, 100_001, 1);
+    assert_eq!(
+        format!("{}", range_step.validate().unwrap_err()),
+        "Parameter range is too large"
+    );
+}
+
 #[test]
 fn test_get_parameterized_commands_int() {
     let commands =
@@ -248,3 +296,19 @@ fn test_get_specified_command_names() {
         .collect::<Vec<String>>();
     assert_eq!(command_names, vec!["name-a", "name-b", "name-c"]);
 }
+
+#[test]
+fn test_different_command_name_count_with_parameters() {
+    let result = build_parameterized_commands(
+        1i32,
+        3i32,
+        1i32,
+        vec!["name-1", "name-2"],
+        vec!["echo {val}"],
+        "val",
+    );
+    assert_eq!(
+        format!("{}", result.unwrap_err()),
+        "Current --command-name count is 2: expected 3 as parameters"
+    );
+}

src/hyperfine/types.rs

@@ -1,7 +1,9 @@
+use rust_decimal::prelude::ToPrimitive;
 use rust_decimal::Decimal;
 /// This module contains common internal types.
 use serde::*;
 use std::collections::BTreeMap;
+use std::convert::TryFrom;
 use std::fmt;
 
 use crate::hyperfine::units::{Second, Unit};
@@ -40,6 +42,20 @@ impl Into<NumericType> for Decimal {
     }
 }
 
+impl TryFrom<NumericType> for usize {
+    type Error = ();
+
+    fn try_from(numeric: NumericType) -> Result<Self, Self::Error> {
+        match numeric {
+            NumericType::Int(i) => usize::try_from(i).map_err(|_| ()),
+            NumericType::Decimal(d) => match d.to_u64() {
+                Some(u) => usize::try_from(u).map_err(|_| ()),
+                None => Err(()),
+            },
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ParameterValue {
     Text(String),

src/main.rs

@@ -255,17 +255,24 @@ fn build_commands<'a>(matches: &'a ArgMatches<'_>) -> Vec<Command<'a>> {
             return Vec::new();
         }
 
+        // `--command-name` should appear exactly once or same count with parameters.
+        let command_name_count = command_names.len();
+        if command_name_count > 1 && command_name_count != param_space_size {
+            let err = OptionsError::DifferentCommandNameCountWithParameters(
+                command_name_count,
+                param_space_size,
+            );
+            error(&err.to_string());
+        }
+
         let mut i = 0;
-        let name_count = command_names.len();
         let mut commands = Vec::with_capacity(param_space_size);
         let mut index = vec![0usize; dimensions.len()];
         'outer: loop {
-            // Sets the command name by index (remainder) if exists.
+            let name = command_names
-            let name = if name_count > 0 {
+                .get(i)
-                Some(command_names[i % name_count])
+                .or_else(|| command_names.get(0))
-            } else {
+                .map(|s| *s);
-                None
-            };
             i += 1;
 
             let (command_index, params_indices) = index.split_first().unwrap();