WIP: Re-implement parser in pest

Parser implementation is kind of iffy. Let's try to re-implement it
using pest.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

Cargo.lock

@@ -37,6 +37,39 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "block-buffer"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0940dc441f31689269e10ac70eb1002a3a1d3ad1390e030043662eb7fe4688b"
+dependencies = [
+ "block-padding",
+ "byte-tools",
+ "byteorder",
+ "generic-array",
+]
+
+[[package]]
+name = "block-padding"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa79dedbb091f449f1f39e53edf88d5dbe95f895dae6135a8d7b881fb5af73f5"
+dependencies = [
+ "byte-tools",
+]
+
+[[package]]
+name = "byte-tools"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3b5ca7a04898ad4bcd41c90c5285445ff5b791899bb1b0abdd2a2aa791211d7"
+
+[[package]]
+name = "byteorder"
+version = "1.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
+
 [[package]]
 name = "clap"
 version = "2.34.0"
@@ -52,6 +85,21 @@ dependencies = [
  "vec_map",
 ]
 
+[[package]]
+name = "digest"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3d0c8c8752312f9713efd397ff63acb9f85585afbf179282e720e7704954dd5"
+dependencies = [
+ "generic-array",
+]
+
+[[package]]
+name = "fake-simd"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e88a8acf291dafb59c2d96e8f59828f3838bb1a70398823ade51a84de6a6deed"
+
 [[package]]
 name = "gc"
 version = "0.4.1"
@@ -73,6 +121,15 @@ dependencies = [
  "synstructure",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffdf9f34f1447443d37393cc6c2b8313aebddcd96906caf34e54c68d8e57d7bd"
+dependencies = [
+ "typenum",
+]
+
 [[package]]
 name = "heck"
 version = "0.3.3"
@@ -103,12 +160,67 @@ version = "0.2.109"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f98a04dce437184842841303488f70d0188c5f51437d2a834dc097eafa909a01"
 
+[[package]]
+name = "maplit"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
+
 [[package]]
 name = "memchr"
 version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
 
+[[package]]
+name = "opaque-debug"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2839e79665f131bdb5782e51f2c6c9599c133c6098982a54c794358bf432529c"
+
+[[package]]
+name = "pest"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10f4872ae94d7b90ae48754df22fd42ad52ce740b8f370b03da4835417403e53"
+dependencies = [
+ "ucd-trie",
+]
+
+[[package]]
+name = "pest_derive"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "833d1ae558dc601e9a60366421196a8d94bc0ac980476d0b67e1d0988d72b2d0"
+dependencies = [
+ "pest",
+ "pest_generator",
+]
+
+[[package]]
+name = "pest_generator"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "99b8db626e31e5b81787b9783425769681b347011cc59471e33ea46d2ea0cf55"
+dependencies = [
+ "pest",
+ "pest_meta",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "pest_meta"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54be6e404f5317079812fc8f9f5279de376d8856929e21c184ecf6bbd692a11d"
+dependencies = [
+ "maplit",
+ "pest",
+ "sha-1",
+]
+
 [[package]]
 name = "proc-macro-error"
 version = "1.0.4"
@@ -168,6 +280,18 @@ version = "0.6.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f497285884f3fcff424ffc933e56d7cbca511def0c9831a7f9b5f6153e3cc89b"
 
+[[package]]
+name = "sha-1"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7d94d0bede923b3cea61f3f1ff57ff8cdfd77b400fb8f9998949e0cf04163df"
+dependencies = [
+ "block-buffer",
+ "digest",
+ "fake-simd",
+ "opaque-debug",
+]
+
 [[package]]
 name = "strsim"
 version = "0.8.0"
@@ -203,6 +327,8 @@ name = "sybil"
 version = "0.1.0"
 dependencies = [
  "gc",
+ "pest",
+ "pest_derive",
  "regex",
  "structopt",
  "thiserror",
@@ -260,6 +386,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcf81ac59edc17cc8697ff311e8f5ef2d99fcbd9817b34cec66f90b6c3dfd987"
+
+[[package]]
+name = "ucd-trie"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
+
 [[package]]
 name = "unicode-segmentation"
 version = "1.8.0"

Cargo.toml

@@ -6,6 +6,8 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+pest = "2.1"
+pest_derive = "2.1"
 thiserror = "1.0"
 structopt = "0.3"
 regex = "1.5"

src/main.rs

@@ -5,10 +5,10 @@ mod scope;
 mod syn;
 mod vm;
 
+use pest::Parser;
 use std::io::Read;
 use std::path::PathBuf;
 use structopt::StructOpt;
-use syn::parser::Parser;
 use vm::{error::RuntimeError, machine::MachineBuilder};
 
 #[derive(Debug, StructOpt)]
@@ -33,11 +33,15 @@ fn main() -> Result {
         (input, "<stdin>".to_string())
     };
 
+    let stmts = syn::peg::parse_file(&text)?;
+
+    /*
     let mut parser = Parser::new(path, text.as_str());
     let mut stmts = Vec::new();
     while !parser.is_eof() {
         stmts.extend(parser.next_stmt_list()?);
     }
+    */
 
     let mut machine = MachineBuilder::default()
         .max_stack_size(opt.max_stack_size)

src/syn/mod.rs

@@ -2,5 +2,6 @@ pub mod ast;
 pub mod error;
 pub mod lexer;
 pub mod parser;
+pub mod peg;
 pub mod span;
 pub mod token;

src/syn/parser.pest

@@ -0,0 +1,24 @@
+WHITESPACE = _{ " " | "\r" | "\t" | "\n" }
+
+int = @{ ASCII_DIGIT+ }
+float = @{ ASCII_DIGIT+ ~ "." ~ ASCII_DIGIT+ ~ ("e" ~ ("+" | "-")? ~ ASCII_DIGIT+)? }
+word_char = @{ ASCII_ALPHA | "_" | "?" | "-" | "+" | "*" | "/" | "=" | "@" | "$" | "%" | "^" | "&" | "|" | "~" }
+word = @{ word_char+ }
+// meta = ${ "%" ~ word }
+str = @{
+    "\"" ~
+    (
+          (!("\"" | "\\") ~ ANY)
+        | "\\" ~ ("n" | "t" | "r" | "b" | "\\" | "\"" | "\'")
+    )* ~
+    "\""
+}
+apply = @{ "!" }
+
+assign = { ":" ~ word }
+atom = { float | int | assign | word | str }
+quote = { "[" ~ stmt* ~ "]" }
+expr = { atom | quote | apply }
+stmt = { expr }
+
+file = { SOI ~ stmt* ~ EOI }

src/syn/peg.rs

@@ -0,0 +1,53 @@
+use crate::syn::ast::*;
+use crate::syn::token::*;
+use pest::{error::Error, iterators::Pair, Parser};
+
+#[derive(pest_derive::Parser)]
+#[grammar = "syn/parser.pest"]
+pub struct SybilParser;
+
+pub type Result<T, E = Error<Rule>> = std::result::Result<T, E>;
+
+fn parse_atom(pair: Pair<Rule>) -> Result<SpAtom> {
+    match pair.as_rule() {
+        Rule::float => todo!(),
+        Rule::int => todo!(),
+        Rule::assign => todo!(),
+        Rule::word => todo!(),
+        Rule::str => todo!(),
+        _ => unreachable!(),
+    }
+}
+
+fn parse_expr(pair: Pair<Rule>) -> Result<SpExpr> {
+    match pair.as_rule() {
+        Rule::atom => {
+            todo!()
+        }
+        Rule::quote => {
+            todo!()
+        }
+        Rule::apply => {
+            todo!()
+        }
+        _ => unreachable!(),
+    }
+}
+
+fn parse_stmt(pair: Pair<Rule>) -> Result<SpStmt> {
+    match pair.as_rule() {
+        Rule::expr => {
+            todo!()
+        }
+        _ => unreachable!(),
+    }
+}
+
+pub fn parse_file(text: &str) -> Result<Vec<SpStmt>> {
+    let input = SybilParser::parse(Rule::file, text)?.next().unwrap();
+    let mut stmts = Vec::new();
+    for pair in input.into_inner() {
+        stmts.push(parse_stmt(pair)?);
+    }
+    Ok(stmts)
+}