Add a ta config set subcommand

This uses `toml_edit` to edit the config file in-place.  For the moment,
it only supports top-level arguments, but can be extended to do other
things later.

cli/src/argparse/config.rs

@@ -0,0 +1,36 @@
+use super::args::{any, arg_matching, literal};
+use super::ArgList;
+use crate::usage;
+use nom::{combinator::*, sequence::*, IResult};
+
+#[derive(Debug, PartialEq)]
+/// A config operation
+pub(crate) enum ConfigOperation {
+    /// Set a configuration value
+    Set(String, String),
+}
+
+impl ConfigOperation {
+    pub(super) fn parse(input: ArgList) -> IResult<ArgList, ConfigOperation> {
+        fn set_to_op(input: (&str, &str, &str)) -> Result<ConfigOperation, ()> {
+            Ok(ConfigOperation::Set(input.1.to_owned(), input.2.to_owned()))
+        }
+        map_res(
+            tuple((
+                arg_matching(literal("set")),
+                arg_matching(any),
+                arg_matching(any),
+            )),
+            set_to_op,
+        )(input)
+    }
+
+    pub(super) fn get_usage(u: &mut usage::Usage) {
+        u.subcommands.push(usage::Subcommand {
+            name: "config set",
+            syntax: "config set <key> <value>",
+            summary: "Set a configuration value",
+            description: "Update Taskchampion configuration file to set key = value",
+        });
+    }
+}

cli/src/argparse/mod.rs

@@ -18,12 +18,14 @@ That is, they contain no references, and have no methods to aid in their executi
 */
 mod args;
 mod command;
+mod config;
 mod filter;
 mod modification;
 mod subcommand;
 
 pub(crate) use args::TaskId;
 pub(crate) use command::Command;
+pub(crate) use config::ConfigOperation;
 pub(crate) use filter::{Condition, Filter};
 pub(crate) use modification::{DescriptionMod, Modification};
 pub(crate) use subcommand::Subcommand;

cli/src/argparse/subcommand.rs

@@ -1,5 +1,5 @@
 use super::args::*;
-use super::{ArgList, DescriptionMod, Filter, Modification};
+use super::{ArgList, ConfigOperation, DescriptionMod, Filter, Modification};
 use crate::usage;
 use nom::{branch::alt, combinator::*, sequence::*, IResult};
 use taskchampion::Status;
@@ -25,6 +25,11 @@ pub(crate) enum Subcommand {
         summary: bool,
     },
 
+    /// Manipulate configuration
+    Config {
+        config_operation: ConfigOperation,
+    },
+
     /// Add a new task
     Add {
         modification: Modification,
@@ -61,6 +66,7 @@ impl Subcommand {
         all_consuming(alt((
             Version::parse,
             Help::parse,
+            Config::parse,
             Add::parse,
             Modify::parse,
             Info::parse,
@@ -74,6 +80,7 @@ impl Subcommand {
     pub(super) fn get_usage(u: &mut usage::Usage) {
         Version::get_usage(u);
         Help::get_usage(u);
+        Config::get_usage(u);
         Add::get_usage(u);
         Modify::get_usage(u);
         Info::get_usage(u);
@@ -131,6 +138,26 @@ impl Help {
     fn get_usage(_u: &mut usage::Usage) {}
 }
 
+struct Config;
+
+impl Config {
+    fn parse(input: ArgList) -> IResult<ArgList, Subcommand> {
+        fn to_subcommand(input: (&str, ConfigOperation)) -> Result<Subcommand, ()> {
+            Ok(Subcommand::Config {
+                config_operation: input.1,
+            })
+        }
+        map_res(
+            tuple((arg_matching(literal("config")), ConfigOperation::parse)),
+            to_subcommand,
+        )(input)
+    }
+
+    fn get_usage(u: &mut usage::Usage) {
+        ConfigOperation::get_usage(u);
+    }
+}
+
 struct Add;
 
 impl Add {
@@ -427,6 +454,19 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_config_set() {
+        assert_eq!(
+            Subcommand::parse(argv!["config", "set", "x", "y"]).unwrap(),
+            (
+                &EMPTY[..],
+                Subcommand::Config {
+                    config_operation: ConfigOperation::Set("x".to_owned(), "y".to_owned())
+                }
+            )
+        );
+    }
+
     #[test]
     fn test_add_description() {
         let subcommand = Subcommand::Add {