Add 'str from' subcommand (#2125)

* add human, precision commands

* add 'str from' subcommand (converted from human/precision commands)

move human tests to str from

* add default locale, platform-specific SystemLocale use

* fix platform specific num-format dependency, remove invalid test

* change 'str from' localization to static num_format::Locale::en

* minor cleanup, nudge ci

* re-attempt ci

crates/nu-cli/src/cli.rs

@@ -307,6 +307,7 @@ pub fn create_default_context(
             whole_stream_command(StrUpcase),
             whole_stream_command(StrCapitalize),
             whole_stream_command(StrFindReplace),
+            whole_stream_command(StrFrom),
             whole_stream_command(StrSubstring),
             whole_stream_command(StrSet),
             whole_stream_command(StrToDatetime),

crates/nu-cli/src/commands.rs

@@ -251,8 +251,8 @@ pub(crate) use sort_by::SortBy;
 pub(crate) use split::{Split, SplitChars, SplitColumn, SplitRow};
 pub(crate) use split_by::SplitBy;
 pub(crate) use str_::{
-    Str, StrCapitalize, StrCollect, StrDowncase, StrFindReplace, StrLength, StrSet, StrSubstring,
-    StrToDatetime, StrToDecimal, StrToInteger, StrTrim, StrUpcase,
+    Str, StrCapitalize, StrCollect, StrDowncase, StrFindReplace, StrFrom, StrLength, StrSet,
+    StrSubstring, StrToDatetime, StrToDecimal, StrToInteger, StrTrim, StrUpcase,
 };
 #[allow(unused_imports)]
 pub(crate) use t_sort_by::TSortBy;

crates/nu-cli/src/commands/str_/from.rs

@@ -0,0 +1,263 @@
+use crate::commands::str_::trim::trim_char;
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{
+    ColumnPath, Primitive, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value,
+};
+use nu_source::Tagged;
+use num_bigint::{BigInt, BigUint, ToBigInt};
+
+// TODO num_format::SystemLocale once platform-specific dependencies are stable (see Cargo.toml)
+use num_format::{Locale, ToFormattedString};
+use num_traits::{Pow, Signed};
+use std::iter;
+
+pub struct SubCommand;
+
+#[derive(Deserialize)]
+struct Arguments {
+    rest: Vec<ColumnPath>,
+    decimals: Option<Tagged<u64>>,
+    #[serde(rename(deserialize = "group-digits"))]
+    group_digits: bool,
+}
+
+#[async_trait]
+impl WholeStreamCommand for SubCommand {
+    fn name(&self) -> &str {
+        "str from"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("str from")
+            .rest(
+                SyntaxShape::ColumnPath,
+                "optionally convert to string by column paths",
+            )
+            .named(
+                "decimals",
+                SyntaxShape::Int,
+                "decimal digits to which to round",
+                Some('d'),
+            )
+            .switch(
+                "group-digits",
+                // TODO according to system localization
+                "group digits, currently by thousand with commas",
+                Some('g'),
+            )
+    }
+
+    fn usage(&self) -> &str {
+        "Converts numeric types to strings. Trims trailing zeros unless decimals parameter is specified."
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        operate(args, registry).await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "round to nearest integer",
+                example: "= 1.7 | str from -d 0",
+                result: Some(vec![UntaggedValue::string("2").into_untagged_value()]),
+            },
+            Example {
+                description: "format large number with localized digit grouping",
+                example: "= 1000000.2 | str from -g",
+                result: Some(vec![
+                    UntaggedValue::string("1,000,000.2").into_untagged_value()
+                ]),
+            },
+        ]
+    }
+}
+
+async fn operate(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let (
+        Arguments {
+            decimals,
+            group_digits,
+            rest: column_paths,
+        },
+        input,
+    ) = args.process(&registry.clone()).await?;
+    let digits = decimals.map(|tagged| tagged.item);
+
+    Ok(input
+        .map(move |v| {
+            if column_paths.is_empty() {
+                match action(&v, v.tag(), digits, group_digits) {
+                    Ok(out) => ReturnSuccess::value(out),
+                    Err(err) => Err(err),
+                }
+            } else {
+                let mut ret = v;
+                for path in &column_paths {
+                    let swapping = ret.swap_data_by_column_path(
+                        path,
+                        Box::new(move |old| action(old, old.tag(), digits, group_digits)),
+                    );
+                    match swapping {
+                        Ok(new_value) => {
+                            ret = new_value;
+                        }
+                        Err(err) => {
+                            return Err(err);
+                        }
+                    }
+                }
+
+                ReturnSuccess::value(ret)
+            }
+        })
+        .to_output_stream())
+}
+
+// TODO If you're using the with-system-locale feature and you're on Windows, Clang 3.9 or higher is also required.
+fn action(
+    input: &Value,
+    tag: impl Into<Tag>,
+    digits: Option<u64>,
+    group_digits: bool,
+) -> Result<Value, ShellError> {
+    match &input.value {
+        UntaggedValue::Primitive(prim) => Ok(UntaggedValue::string(match prim {
+            Primitive::Int(int) => {
+                if group_digits {
+                    format_bigint(int) // int.to_formatted_string(*locale)
+                } else {
+                    int.to_string()
+                }
+            }
+            Primitive::Decimal(dec) => format_decimal(dec.clone(), digits, group_digits),
+            _ => {
+                return Err(ShellError::unimplemented(
+                    "str from for non-numeric primitives",
+                ))
+            }
+        })
+        .into_value(tag)),
+        UntaggedValue::Row(_) => Err(ShellError::labeled_error(
+            "specify column to use 'str from'",
+            "found table",
+            input.tag.clone(),
+        )),
+        _ => Err(ShellError::unimplemented(
+            "str from for non-primitive, non-table types",
+        )),
+    }
+}
+
+fn format_bigint(int: &BigInt) -> String {
+    int.to_formatted_string(&Locale::en)
+
+    // TODO once platform-specific dependencies are stable (see Cargo.toml)
+    // #[cfg(windows)]
+    // {
+    //     int.to_formatted_string(&Locale::en)
+    // }
+    // #[cfg(not(windows))]
+    // {
+    //     match SystemLocale::default() {
+    //         Ok(locale) => int.to_formatted_string(&locale),
+    //         Err(_) => int.to_formatted_string(&Locale::en),
+    //     }
+    // }
+}
+
+fn format_decimal(mut decimal: BigDecimal, digits: Option<u64>, group_digits: bool) -> String {
+    if let Some(n) = digits {
+        decimal = round_decimal(&decimal, n)
+    }
+
+    if decimal.is_integer() && (digits.is_none() || digits == Some(0)) {
+        let int = decimal
+            .to_bigint()
+            .expect("integer BigDecimal should convert to BigInt");
+        return if group_digits {
+            int.to_string()
+        } else {
+            format_bigint(&int)
+        };
+    }
+
+    let (int, exp) = decimal.as_bigint_and_exponent();
+    let factor = BigInt::from(10).pow(BigUint::from(exp as u64)); // exp > 0 for non-int decimal
+    let int_part = &int / &factor;
+    let dec_part = (&int % &factor)
+        .abs()
+        .to_biguint()
+        .expect("BigInt::abs should always produce positive signed BigInt and thus BigUInt")
+        .to_str_radix(10);
+
+    let dec_str = if let Some(n) = digits {
+        dec_part
+            .chars()
+            .chain(iter::repeat('0'))
+            .take(n as usize)
+            .collect()
+    } else {
+        trim_char(dec_part, '0', false, true)
+    };
+
+    let format_default_loc = |int_part: BigInt| {
+        let loc = Locale::en;
+        let (int_str, sep) = (
+            int_part.to_formatted_string(&loc),
+            String::from(loc.decimal()),
+        );
+
+        format!("{}{}{}", int_str, sep, dec_str)
+    };
+
+    format_default_loc(int_part)
+
+    // TODO once platform-specific dependencies are stable (see Cargo.toml)
+    // #[cfg(windows)]
+    // {
+    //     format_default_loc(int_part)
+    // }
+    // #[cfg(not(windows))]
+    // {
+    //     match SystemLocale::default() {
+    //         Ok(sys_loc) => {
+    //             let int_str = int_part.to_formatted_string(&sys_loc);
+    //             let sep = String::from(sys_loc.decimal());
+    //             format!("{}{}{}", int_str, sep, dec_str)
+    //         }
+    //         Err(_) => format_default_loc(int_part),
+    //     }
+    // }
+}
+
+fn round_decimal(decimal: &BigDecimal, mut digits: u64) -> BigDecimal {
+    let mut mag = decimal.clone();
+    while mag >= BigDecimal::from(1) {
+        mag = mag / 10;
+        digits += 1;
+    }
+
+    decimal.with_prec(digits)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::SubCommand;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-cli/src/commands/str_/mod.rs

@@ -3,6 +3,7 @@ mod collect;
 mod command;
 mod downcase;
 mod find_replace;
+mod from;
 mod length;
 mod set;
 mod substring;
@@ -17,6 +18,7 @@ pub use collect::SubCommand as StrCollect;
 pub use command::Command as Str;
 pub use downcase::SubCommand as StrDowncase;
 pub use find_replace::SubCommand as StrFindReplace;
+pub use from::SubCommand as StrFrom;
 pub use length::SubCommand as StrLength;
 pub use set::SubCommand as StrSet;
 pub use substring::SubCommand as StrSubstring;

crates/nu-cli/src/commands/str_/trim.rs

@@ -108,6 +108,34 @@ fn action(input: &Value, tag: impl Into<Tag>) -> Result<Value, ShellError> {
     }
 }
 
+// TODO make callable using flag
+pub fn trim_char(s: String, to_trim: char, leading: bool, trailing: bool) -> String {
+    let mut trimmed = String::from("");
+    let mut backlog = String::from("");
+    let mut at_left = true;
+    s.chars().for_each(|ch| match ch {
+        c if c == to_trim => {
+            if !(leading && at_left) {
+                if trailing {
+                    backlog.push(c)
+                } else {
+                    trimmed.push(c)
+                }
+            }
+        }
+        other => {
+            at_left = false;
+            if trailing {
+                trimmed.push_str(backlog.as_str());
+                backlog = String::from("");
+            }
+            trimmed.push(other);
+        }
+    });
+
+    trimmed
+}
+
 #[cfg(test)]
 mod tests {
     use super::{action, SubCommand};