Generate accessors for public struct fields

Automatically infer public struct fields as "JS wants to access this" and
generate appropriate getters/setters for the field. At this time the field is
required to implement `Copy`, but we will probably want to relax that in the
future to at least encompass `JsValue` and maybe other `Clone` values as well.

Closes #121

crates/shared/src/lib.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-pub const SCHEMA_VERSION: &str = "2";
+pub const SCHEMA_VERSION: &str = "3";
 
 #[derive(Deserialize)]
 pub struct ProgramOnlySchema {
@@ -14,7 +14,7 @@ pub struct Program {
     pub exports: Vec<Export>,
     pub enums: Vec<Enum>,
     pub imports: Vec<Import>,
-    pub structs: Vec<String>,
+    pub structs: Vec<Struct>,
     pub version: String,
     pub schema_version: String,
 }
@@ -82,6 +82,17 @@ pub struct Function {
     pub name: String,
 }
 
+#[derive(Deserialize, Serialize)]
+pub struct Struct {
+    pub name: String,
+    pub fields: Vec<StructField>,
+}
+
+#[derive(Deserialize, Serialize)]
+pub struct StructField {
+    pub name: String,
+}
+
 pub fn new_function(struct_name: &str) -> String {
     let mut name = format!("__wbg_");
     name.extend(struct_name
@@ -114,6 +125,26 @@ pub fn struct_function_export_name(struct_: &str, f: &str) -> String {
     return name
 }
 
+pub fn struct_field_get(struct_: &str, f: &str) -> String {
+    let mut name = String::from("__wbg_get_");
+    name.extend(struct_
+        .chars()
+        .flat_map(|s| s.to_lowercase()));
+    name.push_str("_");
+    name.push_str(f);
+    return name
+}
+
+pub fn struct_field_set(struct_: &str, f: &str) -> String {
+    let mut name = String::from("__wbg_set_");
+    name.extend(struct_
+        .chars()
+        .flat_map(|s| s.to_lowercase()));
+    name.push_str("_");
+    name.push_str(f);
+    return name
+}
+
 pub fn version() -> String {
     let mut v = env!("CARGO_PKG_VERSION").to_string();
     if let Some(s) = option_env!("WBG_VERSION") {