♻️ Major code restructuring

src/config/path.rs

@@ -0,0 +1,167 @@
+use crate::config::error::*;
+use crate::config::value::{Value, ValueKind};
+
+use std::collections::HashMap;
+use std::str::FromStr;
+
+mod parser;
+
+#[derive(Debug, Eq, PartialEq, Clone, Hash)]
+pub enum Expression {
+    Identifier(String),
+    Child(Box<Expression>, String),
+    Subscript(Box<Expression>, isize),
+}
+
+impl FromStr for Expression {
+    type Err = ConfigError;
+
+    fn from_str(s: &str) -> Result<Expression> {
+        parser::from_str(s).map_err(ConfigError::PathParse)
+    }
+}
+
+fn sindex_to_uindex(index: isize, len: usize) -> usize {
+    if index >= 0 {
+        index as usize
+    } else {
+        len - (index.unsigned_abs())
+    }
+}
+
+impl Expression {
+    pub fn get_mut_forcibly<'a>(&self, root: &'a mut Value) -> Option<&'a mut Value> {
+        match *self {
+            Expression::Identifier(ref id) => match root.kind {
+                ValueKind::Table(ref mut map) => Some(
+                    map.entry(id.clone())
+                        .or_insert_with(|| Value::new(None, ValueKind::Nil)),
+                ),
+
+                _ => None,
+            },
+
+            Expression::Child(ref expr, ref key) => match expr.get_mut_forcibly(root) {
+                Some(value) => match value.kind {
+                    ValueKind::Table(ref mut map) => Some(
+                        map.entry(key.clone())
+                            .or_insert_with(|| Value::new(None, ValueKind::Nil)),
+                    ),
+
+                    _ => {
+                        *value = HashMap::<String, Value>::new().into();
+
+                        if let ValueKind::Table(ref mut map) = value.kind {
+                            Some(
+                                map.entry(key.clone())
+                                    .or_insert_with(|| Value::new(None, ValueKind::Nil)),
+                            )
+                        } else {
+                            unreachable!();
+                        }
+                    }
+                },
+
+                _ => None,
+            },
+
+            Expression::Subscript(ref expr, index) => match expr.get_mut_forcibly(root) {
+                Some(value) => {
+                    match value.kind {
+                        ValueKind::Array(_) => (),
+                        _ => *value = Vec::<Value>::new().into(),
+                    }
+
+                    match value.kind {
+                        ValueKind::Array(ref mut array) => {
+                            let index = sindex_to_uindex(index, array.len());
+
+                            if index >= array.len() {
+                                array.resize(index + 1, Value::new(None, ValueKind::Nil));
+                            }
+
+                            Some(&mut array[index])
+                        }
+
+                        _ => None,
+                    }
+                }
+                _ => None,
+            },
+        }
+    }
+
+    pub fn set(&self, root: &mut Value, value: Value) {
+        match *self {
+            Expression::Identifier(ref id) => {
+                // Ensure that root is a table.
+                match root.kind {
+                    ValueKind::Table(_) => {}
+
+                    _ => {
+                        *root = HashMap::<String, Value>::new().into();
+                    }
+                }
+
+                match value.kind {
+                    ValueKind::Table(ref incoming_map) => {
+                        // Pull out another table.
+                        let target = if let ValueKind::Table(ref mut map) = root.kind {
+                            map.entry(id.clone())
+                                .or_insert_with(|| HashMap::<String, Value>::new().into())
+                        } else {
+                            unreachable!();
+                        };
+
+                        // Continue the deep merge.
+                        for (key, val) in incoming_map {
+                            Expression::Identifier(key.clone()).set(target, val.clone());
+                        }
+                    }
+
+                    _ => {
+                        if let ValueKind::Table(ref mut map) = root.kind {
+                            // Just do a simple set.
+                            map.insert(id.clone(), value);
+                        }
+                    }
+                }
+            }
+
+            Expression::Child(ref expr, ref key) => {
+                if let Some(parent) = expr.get_mut_forcibly(root) {
+                    match parent.kind {
+                        ValueKind::Table(_) => {
+                            Expression::Identifier(key.clone()).set(parent, value);
+                        }
+
+                        _ => {
+                            // Didn't find a table. Oh well. Make a table and do this anyway.
+                            *parent = HashMap::<String, Value>::new().into();
+
+                            Expression::Identifier(key.clone()).set(parent, value);
+                        }
+                    }
+                }
+            }
+
+            Expression::Subscript(ref expr, index) => {
+                if let Some(parent) = expr.get_mut_forcibly(root) {
+                    match parent.kind {
+                        ValueKind::Array(_) => (),
+                        _ => *parent = Vec::<Value>::new().into(),
+                    }
+
+                    if let ValueKind::Array(ref mut array) = parent.kind {
+                        let uindex = sindex_to_uindex(index, array.len());
+                        if uindex >= array.len() {
+                            array.resize(uindex + 1, Value::new(None, ValueKind::Nil));
+                        }
+
+                        array[uindex] = value;
+                    }
+                }
+            }
+        }
+    }
+}