wasm first steps

gpx-rs/src/stack.rs

@@ -0,0 +1,101 @@
+use std::{collections::HashMap, rc::Rc};
+
+use crate::types::{GPXFile, GPXFileId};
+
+#[derive(Default)]
+pub struct Stack {
+    entries: Vec<StackEntry>,
+    index: Option<usize>,
+}
+
+impl Stack {
+    pub fn current(&self) -> Option<&StackEntry> {
+        match self.index {
+            Some(i) => Some(&self.entries[i]),
+            None => None,
+        }
+    }
+
+    pub fn get_new_file_id(&self) -> GPXFileId {
+        if let Some(current) = self.current() {
+            for id in 0..current.len() {
+                if !current.contains_key(&id) {
+                    return id;
+                }
+            }
+            current.len() as GPXFileId
+        } else {
+            0
+        }
+    }
+
+    pub fn update(&mut self, files: &[Rc<GPXFile>]) {
+        let mut next = match self.current() {
+            Some(current) => current.clone(),
+            None => StackEntry::default(),
+        };
+        for file in files {
+            next.insert(file.id, file.clone());
+        }
+        self.push(next);
+    }
+
+    pub fn delete(&mut self, files: &[GPXFileId]) {
+        if let Some(current) = self.current() {
+            let mut next = current.clone();
+            for file in files {
+                next.remove(file);
+            }
+            self.push(next);
+        }
+    }
+
+    pub fn can_undo(&self) -> bool {
+        self.index.is_some()
+    }
+
+    pub fn can_redo(&self) -> bool {
+        match self.index {
+            Some(i) => i + 1 < self.entries.len(),
+            None => !self.entries.is_empty(),
+        }
+    }
+
+    pub fn undo(&mut self) {
+        if let Some(i) = self.index {
+            if i == 0 {
+                self.index = None;
+            } else {
+                self.index = Some(i - 1);
+            }
+        }
+    }
+
+    pub fn redo(&mut self) {
+        match self.index {
+            Some(i) => {
+                if i + 1 < self.entries.len() {
+                    self.index = Some(i + 1);
+                }
+            }
+            None => {
+                if !self.entries.is_empty() {
+                    self.index = Some(0);
+                }
+            }
+        }
+    }
+
+    fn push(&mut self, entry: StackEntry) {
+        if let Some(i) = self.index {
+            if i + 1 < self.entries.len() {
+                self.entries.truncate(i + 1);
+            }
+        }
+
+        self.entries.push(entry);
+        self.index = Some(self.entries.len() - 1);
+    }
+}
+
+pub type StackEntry = HashMap<GPXFileId, Rc<GPXFile>>;