feat: Add configuration for add_newline (#116)

- Replace TableExt with a Config trait that extends toml::value::Table
Add configuration for add_newline
- add_newline is a root-level configuration value. When set to false, the initial newline before the prompt is removed.

7 files changed, 73 insertions, 28 deletions

diff --git a/docs/config/README.md b/docs/config/README.md
index c9cf35ca0..fdcb07aea 100644
--- a/docs/config/README.md
+++ b/docs/config/README.md
@@ -14,6 +14,9 @@ $ touch ~/.config/starship.toml
 All configuration for starship is done in this [TOML](https://github.com/toml-lang/toml) file:
 
 ```toml
+# Don't print a new line at the start of the prompt
+add_newline = false
+
 # Replace the "➜" symbol in the prompt with "❯"
 [character]      # The name of the module we are confguring is "character"
 symbol = "❯"     # The "symbol" segment is being set to "❯"
@@ -37,6 +40,24 @@ are segments within it. Every module also has a prefix and suffix that are the d
  "via "         "⬢"        "v10.4.1"       ""
 ```
 
+## Prompt
+
+This is the list of prompt-wide configuration options.
+
+### Options
+
+| Variable | Default | Description|
+| `add_newline` | `true` | Add a new line before the start of the prompt |
+
+### Example
+
+```toml
+# ~/.config/starship.toml
+
+# Disable the newline at the start of the prompt
+add_newline = false
+```
+
 ## Battery
 
 The `battery` module shows how charged the device's battery is and its current charging status.
diff --git a/src/config.rs b/src/config.rs
index f2045a688..d5861b9f0 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -2,25 +2,33 @@ use crate::utils;
 use std::env;
 
 use dirs::home_dir;
+use toml::value::Table;
 
-pub struct Config {
-    data: toml::value::Table,
+pub trait Config {
+    fn initialize() -> Table;
+    fn config_from_file() -> Option<Table>;
+    fn get_module_config(&self, module_name: &str) -> Option<&Table>;
+
+    // Config accessor methods
+    fn get_as_bool(&self, key: &str) -> Option<bool>;
+    fn get_as_str(&self, key: &str) -> Option<&str>;
+
+    // Internal implementation for accessors
+    fn get_config(&self, key: &str) -> Option<&toml::value::Value>;
 }
 
-impl Config {
+impl Config for Table {
     /// Initialize the Config struct
-    pub fn initialize() -> Config {
-        if let Some(file_data) = Config::config_from_file() {
-            return Config { data: file_data };
+    fn initialize() -> Table {
+        if let Some(file_data) = Table::config_from_file() {
+            return file_data;
         }
 
-        Config {
-            data: toml::value::Table::new(),
-        }
+        Table::new()
     }
 
     /// Create a config from a starship configuration file
-    fn config_from_file() -> Option<toml::value::Table> {
+    fn config_from_file() -> Option<Table> {
         let file_path = match env::var("STARSHIP_CONFIG") {
             Ok(path) => {
                 // Use $STARSHIP_CONFIG as the config path if available
@@ -55,9 +63,8 @@ impl Config {
     }
 
     /// Get the subset of the table for a module by its name
-    pub fn get_module_config(&self, module_name: &str) -> Option<&toml::value::Table> {
+    fn get_module_config(&self, module_name: &str) -> Option<&toml::value::Table> {
         let module_config = self
-            .data
             .get(module_name)
             .map(toml::Value::as_table)
             .unwrap_or(None);
@@ -74,16 +81,7 @@ impl Config {
 
         module_config
     }
-}
-
-/// Extends `toml::value::Table` with useful methods
-pub trait TableExt {
-    fn get_config(&self, key: &str) -> Option<&toml::value::Value>;
-    fn get_as_bool(&self, key: &str) -> Option<bool>;
-    fn get_as_str(&self, key: &str) -> Option<&str>;
-}
 
-impl TableExt for toml::value::Table {
     /// Get the config value for a given key
     fn get_config(&self, key: &str) -> Option<&toml::value::Value> {
         log::trace!("Looking for config key \"{}\"", key);
diff --git a/src/context.rs b/src/context.rs
index e8ca107f1..3e3640ace 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -1,4 +1,4 @@
-use crate::config::{Config, TableExt};
+use crate::config::Config;
 use crate::module::Module;
 
 use clap::ArgMatches;
@@ -13,7 +13,7 @@ use std::path::PathBuf;
 /// of the prompt.
 pub struct Context<'a> {
     /// The deserialized configuration map from the user's `starship.toml` file.
-    pub config: Config,
+    pub config: toml::value::Table,
 
     /// The current working directory that starship is being called in.
     pub current_dir: PathBuf,
@@ -51,7 +51,7 @@ impl<'a> Context<'a> {
     where
         T: Into<PathBuf>,
     {
-        let config = Config::initialize();
+        let config = toml::value::Table::initialize();
 
         // TODO: Currently gets the physical directory. Get the logical directory.
         let current_dir = Context::expand_tilde(dir.into());
diff --git a/src/module.rs b/src/module.rs
index 3e530c3f6..af985ea3a 100644
--- a/src/module.rs
+++ b/src/module.rs
@@ -1,4 +1,4 @@
-use crate::config::TableExt;
+use crate::config::Config;
 use crate::segment::Segment;
 use ansi_term::Style;
 use ansi_term::{ANSIString, ANSIStrings};
diff --git a/src/print.rs b/src/print.rs
index ae712e123..3cd185e41 100644
--- a/src/print.rs
+++ b/src/print.rs
@@ -2,6 +2,7 @@ use clap::ArgMatches;
 use rayon::prelude::*;
 use std::io::{self, Write};
 
+use crate::config::Config;
 use crate::context::Context;
 use crate::module::Module;
 use crate::modules;
@@ -23,12 +24,15 @@ const PROMPT_ORDER: &[&str] = &[
 
 pub fn prompt(args: ArgMatches) {
     let context = Context::new(args);
+    let config = &context.config;
 
     let stdout = io::stdout();
     let mut handle = stdout.lock();
 
     // Write a new line before the prompt
-    writeln!(handle).unwrap();
+    if config.get_as_bool("add_newline") != Some(false) {
+        writeln!(handle).unwrap();
+    }
 
     let modules = PROMPT_ORDER
         .par_iter()
diff --git a/tests/testsuite/common.rs b/tests/testsuite/common.rs
index ee817d8d5..a2bc10f12 100644
--- a/tests/testsuite/common.rs
+++ b/tests/testsuite/common.rs
@@ -9,8 +9,8 @@ lazy_static! {
     static ref EMPTY_CONFIG: PathBuf = MANIFEST_DIR.join("empty_config.toml");
 }
 
-/// Run an instance of starship
-fn run_starship() -> process::Command {
+/// Render the full starship prompt
+pub fn render_prompt() -> process::Command {
     let mut command = process::Command::new("./target/debug/starship");
 
     command
@@ -22,6 +22,7 @@ fn run_starship() -> process::Command {
     command
 }
 
+/// Render a specific starship module by name
 pub fn render_module(module_name: &str) -> process::Command {
     let mut command = process::Command::new("./target/debug/starship");
 
diff --git a/tests/testsuite/configuration.rs b/tests/testsuite/configuration.rs
index 189ee3658..a9daefb63 100644
--- a/tests/testsuite/configuration.rs
+++ b/tests/testsuite/configuration.rs
@@ -32,3 +32,24 @@ fn disabled_module() -> io::Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn add_newline_configuration() -> io::Result<()> {
+    // Start prompt with newline
+    let default_output = common::render_prompt().output()?;
+    let actual = String::from_utf8(default_output.stdout).unwrap();
+    let expected = actual.trim_start();
+    assert_ne!(actual, expected);
+
+    // Start prompt without newline
+    let output = common::render_prompt()
+        .use_config(toml::toml! {
+            add_newline = false
+        })
+        .output()?;
+    let actual = String::from_utf8(output.stdout).unwrap();
+    let expected = actual.trim_start();
+    assert_eq!(expected, actual);
+
+    Ok(())
+}