From a6d065864cd8191395848d02a7fd09acea108aa5 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Fri, 14 Feb 2020 01:50:24 -0800
Subject: [PATCH] A lot of stuff around identifiers

---
 schala-lang/language/src/parser.rs | 76 +++++++++++++++++++++++++-----
 1 file changed, 64 insertions(+), 12 deletions(-)

diff --git a/schala-lang/language/src/parser.rs b/schala-lang/language/src/parser.rs
index 8a4e234..b632e89 100644
--- a/schala-lang/language/src/parser.rs
+++ b/schala-lang/language/src/parser.rs
@@ -4,28 +4,45 @@ use std::rc::Rc;
 use std::str::FromStr;
 
 use nom::IResult;
-use nom::character::complete::{one_of, space0};
-use nom::bytes::complete::{tag, take_while, take_until};
-use nom::combinator::{map, map_res, value, opt};
-use nom::multi::many1;
-use nom::error::{ParseError, ErrorKind};
+use nom::character::complete::{one_of, space0, alphanumeric0};
+use nom::bytes::complete::{tag, take, take_while, take_until};
+use nom::combinator::{map, map_res, value, opt, verify};
+use nom::multi::{separated_list, many1, many0};
+//use nom::error::{ParseError, ErrorKind};
 use nom::branch::alt;
-use nom::sequence::delimited;
+use nom::sequence::{pair, delimited};
 
 use crate::ast::*;
 use crate::builtin::Builtin;
 
 
-const OPERATOR_CHARS: &'static str = "~`!@#$%^&*-+=<>?/|";
+fn single_alphabetic_character(text: &str) -> IResult<&str, char> {
+  let p = verify(take(1usize), |s: &str| s.chars().nth(0).map(|c| c.is_alphabetic()).unwrap_or(false));
+  map(p, |s: &str| s.chars().nth(0).unwrap())(text)
+}
 
+fn single_alphanumeric_character(text: &str) -> IResult<&str, char> {
+  let p = verify(take(1usize), |s: &str| s.chars().nth(0).map(|c| c.is_alphanumeric() || c == '_').unwrap_or(false));
+  map(p, |s: &str| s.chars().nth(0).unwrap())(text)
+}
+
+fn identifier(text: &str) -> IResult<&str, Rc<String>> {
+  use nom::character::complete::char;
+  map(alt((
+    pair(char('_'), many1(single_alphanumeric_character)),
+    pair(single_alphabetic_character, many0(single_alphanumeric_character))
+  )),
+  |(first, rest): (char, Vec<char>)| Rc::new(format!("{}{}", first, rest.into_iter().collect::<String>()))
+  )(text)
+}
+
+const OPERATOR_CHARS: &'static str = "~`!@#$%^&*-+=<>?/|";
 fn parse_binop(input: &str) -> IResult<&str, BinOp> {
-  use nom::character::complete::one_of;
   let (rest, op): (_, Vec<char>) = many1(one_of(OPERATOR_CHARS))(input)?;
   let sigil: String = op.into_iter().collect();
   Ok((rest, BinOp::from_sigil(&sigil)))
 }
 
-
 fn parse_bool_literal(input: &str) -> IResult<&str, ExpressionKind> {
   let p = alt((
     value(true, tag("true")),
@@ -79,7 +96,7 @@ fn parse_string_literal(text: &str) -> IResult<&str, ExpressionKind> {
   Ok((text, expr))
 }
 
-fn parse_literal(input: &str) -> IResult<&str, ExpressionKind> {
+fn literal(input: &str) -> IResult<&str, ExpressionKind> {
   alt((
     parse_string_literal,
     parse_hex_literal,
@@ -100,11 +117,45 @@ fn prefix_op(input: &str) -> IResult<&str, PrefixOp> {
   map(p, |sigil| PrefixOp::from_str(&sigil.to_string()).unwrap())(input)
 }
 
+fn primary_expr(text: &str) -> IResult<&str, ExpressionKind> {
+  // primary := literal | paren_expr | if_expr | for_expr | while_expr | identifier_expr | lambda_expr | anonymous_struct | list_expr
+
+  alt((
+    literal,
+    paren_expr,
+  ))(text)
+}
+
+fn invocation_argument(text: &str) -> IResult<&str, InvocationArgument> {
+  use nom::character::complete::char;
+  alt((
+    value(InvocationArgument::Ignored, pair(char('_'), alphanumeric0)),
+    map(expression_kind, |kind: ExpressionKind| InvocationArgument::Positional(
+        Expression {  id: ItemId::new(0), kind, type_anno: None }))
+    //map(identifier, |id: Rc<String>| 
+  ))(text)
+}
+
+fn call_expr(text: &str) -> IResult<&str, ExpressionKind> {
+  use nom::character::complete::char;
+  let (text, expr) = primary_expr(text)?;
+  let (text, call_part) = opt(
+    delimited(char('('), separated_list(char(','), invocation_argument), char(')'))
+  )(text)?;
+  let output = if let Some(arguments) = call_part {
+    let f = bx!(Expression { id: ItemId::new(0), kind: expr, type_anno: None }); 
+    ExpressionKind::Call { f, arguments }
+  } else {
+    expr
+  };
+  Ok((text, output))
+}
+
 fn prefix_expr(text: &str) -> IResult<&str, ExpressionKind> {
   let (text, pfx) = delimited(space0, opt(prefix_op), space0)(text)?;
   let (text, result) = alt((
     paren_expr,
-    parse_literal
+    literal,
   ))(text)?;
   match pfx {
     None => Ok((text, result)),
@@ -145,6 +196,7 @@ fn expression_kind(input: &str) -> IResult<&str, ExpressionKind> {
 }
 
 pub fn perform_parsing(input: &str) -> Result<String, String> {
-  let output = expression_kind(input);
+  //let output = expression_kind(input);
+  let output = identifier(input);
   Ok(format!("{:?}", output))
 }