Testing simple grammar

.gitignore

@@ -26,3 +26,4 @@ target
 /target
 
 /test/build
+/test/output.json

src/main.rs

@@ -30,6 +30,13 @@ fn main() {
             }
             cmd_check(&args[2]);
         }
+        "parse" => {
+            if args.len() < 3 {
+                eprintln!("error: expected a file path\n  usage: mist check <file.ms>");
+                process::exit(1);
+            }
+            cmd_parse(&args[2]);
+        }
         "version" | "--version" | "-v" => {
             println!("mist {}", env!("CARGO_PKG_VERSION"));
         }
@@ -61,6 +68,26 @@ fn cmd_check(path: &str) {
     }
 }
 
+fn cmd_parse(path: &str) {
+    let source = read_ms_file(path);
+    match parser::parse(&source) {
+        Ok(output) => {
+            fs::write(
+                "output.json",
+                serde_json::to_string_pretty(&output).unwrap(),
+            )
+            .unwrap_or_else(|e| {
+                eprintln!("error: could not write output.json: {}", e);
+                process::exit(1);
+            });
+        }
+        Err(e) => {
+            eprintln!("parse error:\n{}", e);
+            process::exit(1);
+        }
+    }
+}
+
 fn read_ms_file(path: &str) -> String {
     let pb = PathBuf::from(path);
 

src/parser/ast.rs

@@ -1,9 +1,11 @@
-#[derive(Debug, Clone)]
+use serde::Serialize;
+
+#[derive(Debug, Clone, Serialize)]
 pub enum TypeExpr {
     Identifier(String),
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Serialize)]
 pub enum TopLevel {
     Import(String),
     StructDecl {
@@ -18,15 +20,20 @@ pub enum TopLevel {
     },
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Serialize)]
 pub enum Statement {
     Expression(String),
 }
 
+#[derive(Debug, Clone, Serialize)]
 pub enum Expression {
     Identifier(String),
     IntLiteral(i64),
     FloatLiteral(f64),
     BoolLiteral(bool),
     StringLiteral(String),
+    FunctionCall {
+        callee: Box<Expression>,
+        args: Vec<Expression>,
+    },
 }

src/parser/grammar.pest

@@ -2,7 +2,7 @@ WHITESPACE = _{ " " | "\t" | "\r" | "\n" }
 COMMENT    = _{ "//" ~ (!"\n" ~ ANY)* }
 
 program =  { SOI ~ item* ~ EOI }
-item    = _{ import_decl | function_decl | struct_decl }
+item    = _{ import_decl | function_decl }
 
 // primitives
 identifier = @{ (ASCII_ALPHA | "_") ~ (ASCII_ALPHANUMERIC | "_")* }
@@ -16,20 +16,15 @@ inner_str  = @{ (!"\"" ~ ANY)* }
 
 import_decl = { "import" ~ string_lit ~ ";" }
 
-struct_field = { identifier ~ ":" ~ type_expr ~ ";" }
-struct_decl  = {
-    "struct" ~ identifier ~ "{" ~ struct_field* ~ "}"
-}
-
 param_list    = { param ~ ("," ~ param)* ~ ","? }
 param         = { identifier ~ ":" ~ type_expr }
 function_decl = {
-    "function" ~ identifier ~ "(" ~ param_list? ~ ")" ~ ("->" ~ type_expr)? ~ block
+    "function" ~ identifier ~ "(" ~ param_list? ~ ")" ~ (":" ~ type_expr)? ~ block
 }
 
 // ================= STATEMENTS =================
 
-block = { "{" ~ statement* ~ "}" }
+block = { "{" ~ "}" }
 
 statement = _{ "idk" }
 

test/src/main.ms

@@ -1,9 +1,3 @@
 import "fmt";
 
-function add(a: int, b: int) -> int {
+function add(a: int, b: int): int {}
-    return a + b;
-}
-
-function main() {
-    fmt.Println(add(10, 10) / 2);
-}