Initial commit

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "toml-merge"
+version = "0.1.0"
+description = "Simple CLI utility which merges TOML files."
+authors = ["Reid Rankin <[email protected]>"]
+license = "ISC"
+repository = "https://github.com/reidrankin/toml-merge"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+json = "0.12.4"
+structopt = "0.3.21"
+toml = "0.5.8"

src/main.rs

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+use json;
+use std::{
+    fs,
+    path::PathBuf,
+};
+use structopt::StructOpt;
+
+#[derive(StructOpt, Debug)]
+struct Opt {
+    /// Output as JSON
+    #[structopt(short, long)]
+    json_out: bool,
+
+    /// Input files. These will be merged in order, so later files take precedence.
+    #[structopt(name = "FILE", parse(from_os_str))]
+    files: Vec<PathBuf>,
+}
+
+fn merge(merged: &mut toml::Value, value: &toml::Value) {
+    match value {
+        toml::Value::String(_) |
+        toml::Value::Integer(_) |
+        toml::Value::Float(_) |
+        toml::Value::Boolean(_) |
+        toml::Value::Datetime(_) => *merged = value.clone(),
+        toml::Value::Array(x) => {
+            match merged {
+                toml::Value::Array(merged) => {
+                    for (k, v) in x.iter().enumerate() {
+                        match merged.get_mut(k) {
+                            Some(x) => merge(x, v),
+                            None => {
+                                let _ = merged.insert(k.clone(), v.clone());
+                            },
+                        }
+                    }
+                },
+                _ => *merged = value.clone(),
+            }
+        },
+        toml::Value::Table(x) => {
+            match merged {
+                toml::Value::Table(merged) => {
+                    for (k, v) in x.iter() {
+                        match merged.get_mut(k) {
+                            Some(x) => merge(x, v),
+                            None => {
+                                let _ = merged.insert(k.clone(), v.clone());
+                            },
+                        }
+                    }
+                },
+                _ => *merged = value.clone(),
+            }
+        },
+    }
+}
+
+fn toml_to_json(x: toml::Value) -> json::JsonValue {
+    match x {
+        toml::Value::String(x) => json::JsonValue::String(x),
+        toml::Value::Integer(x) => json::JsonValue::Number(x.into()),
+        toml::Value::Float(x) => json::JsonValue::Number(x.into()),
+        toml::Value::Boolean(x) => json::JsonValue::Boolean(x),
+        toml::Value::Datetime(x) => json::JsonValue::String(x.to_string()),
+        toml::Value::Array(x) => json::JsonValue::Array(x.into_iter().map(toml_to_json).collect()),
+        toml::Value::Table(x) => json::JsonValue::Object(x.into_iter().map(|(k, v)| (k, toml_to_json(v))).collect()),
+    }
+}
+
+fn main() {
+    let opt = Opt::from_args();
+
+    let mut merged: toml::Value = toml::Value::Table(toml::value::Table::new());
+    for file in opt.files.iter() {
+        let value: toml::value::Table = toml::from_slice(&fs::read(file).expect(&format!("Error reading {:?}", file))).expect(&format!("Expected TOML table in {:?}", file));
+        merge(&mut merged, &toml::Value::Table(value));
+    }
+
+    if opt.json_out {
+        println!("{}", json::stringify(toml_to_json(merged)));
+    } else {
+        println!("{}", merged.to_string());
+    }
+}