From dd9a1b8a2ed473c24857bd857a1e7f514f7bbc0a Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Sun, 8 Mar 2020 05:11:00 -0700
Subject: [PATCH] Whole lot of added code around if exprs

---
 schala-lang/language/src/parser.rs | 109 ++++++++++++++++++++++++++---
 1 file changed, 99 insertions(+), 10 deletions(-)

diff --git a/schala-lang/language/src/parser.rs b/schala-lang/language/src/parser.rs
index b02ab5e..5d4fbe4 100644
--- a/schala-lang/language/src/parser.rs
+++ b/schala-lang/language/src/parser.rs
@@ -10,7 +10,7 @@ use nom::combinator::{cut, map, map_res, value, opt, verify};
 use nom::multi::{separated_list, separated_nonempty_list, many1, many0};
 use nom::error::{context, ParseError, VerboseError};
 use nom::branch::alt;
-use nom::sequence::{pair, delimited, preceded};
+use nom::sequence::{pair, tuple, delimited, preceded};
 
 use crate::ast::*;
 use crate::builtin::Builtin;
@@ -26,6 +26,10 @@ where
       delimited(space0, parser, space0)
     }
 
+fn statement_sep(text: &str) -> ParseResult<()> {
+  value((), one_of("\n;"))(text)
+}
+
 fn single_alphabetic_character(text: &str) -> ParseResult<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)
@@ -124,18 +128,15 @@ fn prefix_op(text: &str) -> ParseResult<PrefixOp> {
   map(p, |sigil| PrefixOp::from_str(&sigil.to_string()).unwrap())(text)
 }
 
-fn identifier_expr(text: &str) -> ParseResult<ExpressionKind> {
-  let (text, qualified_identifier) = map(
-    qualified_identifier_list,
+fn qualified_name(text: &str) -> ParseResult<QualifiedName> {
+  map(
+    separated_nonempty_list(tag("::"), identifier),
     |components| QualifiedName { id: ItemId::new(0), components }
-  )(text)?;
-  //TODO handle struct literals
-  let exp = Expression::new(ItemId::new(0), ExpressionKind::Value(qualified_identifier));
-  Ok((text, exp.kind))
+  )(text)
 }
 
-fn qualified_identifier_list(text: &str) -> ParseResult<Vec<Rc<String>>> {
-  separated_nonempty_list(tag("::"), identifier)(text)
+fn identifier_expr(text: &str) -> ParseResult<ExpressionKind> {
+  map(qualified_name, ExpressionKind::Value)(text)
 }
 
 fn primary_expr(text: &str) -> ParseResult<ExpressionKind> {
@@ -173,6 +174,94 @@ fn if_expr(text: &str) -> ParseResult<ExpressionKind> {
 }
 */
 
+fn if_expr_body(text: &str) -> ParseResult<IfExpressionBody> {
+  alt((
+    preceded(tag("then"), simple_conditional),
+    preceded(tag("is"), simple_pattern_match),
+    cond_block,
+  ))(text)
+}
+
+fn simple_conditional(text: &str) -> ParseResult<IfExpressionBody> {
+  map(
+    pair(expr_or_block, else_case),
+    |(then_case, else_case)| IfExpressionBody::SimpleConditional { then_case, else_case }
+  )(text)
+}
+
+fn else_case(text: &str) -> ParseResult<Option<Block>> {
+  opt(preceded(tag("else"), expr_or_block))(text)
+}
+
+fn simple_pattern_match(text: &str) -> ParseResult<IfExpressionBody> {
+  let p = tuple((pattern, tag("then"), expr_or_block, else_case));
+  map(p, |(pattern, _, then_case, else_case)| 
+    IfExpressionBody::SimplePatternMatch { pattern, then_case, else_case }
+  )(text)
+}
+
+fn pattern(text: &str) -> ParseResult<Pattern> {
+  use nom::character::complete::char;
+
+  let t = delimited(char('('), 
+    separated_nonempty_list(char(','), pattern),
+    char(')')
+  );
+
+  alt((
+    map(t, |patterns| Pattern::TuplePattern(patterns)),
+    simple_pattern,
+  ))(text)
+}
+
+fn simple_pattern(text: &str) -> ParseResult<Pattern> {
+  alt((
+    value(Pattern::Ignored, tag("_")),
+    tuple_struct_pattern,
+    record_pattern,
+    map(pattern_literal, Pattern::Literal),
+    map(qualified_name, Pattern::VarOrName),
+  ))(text)
+}
+
+fn tuple_struct_pattern(text: &str) -> ParseResult<Pattern> {
+  unimplemented!()
+}
+
+fn record_pattern(text: &str) -> ParseResult<Pattern> {
+  unimplemented!()
+}
+
+fn pattern_literal(text: &str) -> ParseResult<PatternLiteral> {
+  use PatternLiteral::*;
+  use nom::character::complete::char;
+  alt((
+    value(BoolPattern(true), tag("true")),
+    value(BoolPattern(false), tag("false")),
+    map(delimited(char('"'), take_until("\""), char('"')), |s: &str| StringPattern(Rc::new(s.to_string()))),
+  ))(text)
+    //TODO handle signed_number_literal
+}
+
+fn cond_block(text: &str) -> ParseResult<IfExpressionBody> {
+  unimplemented!()
+}
+
+fn expr_or_block(text: &str) -> ParseResult<Block> {
+  //TODO fix
+  alt((block, map(expression, |expr| vec![Statement { id: ItemId::new(0), kind: StatementKind::Expression(expr)}])))(text)
+}
+
+fn block(text: &str) -> ParseResult<Block> {
+  use nom::character::complete::char;
+  //TODO fix this so it can handle nested statements
+  delimited(char('{'),
+    separated_nonempty_list(statement_sep,
+      map(expression, |e| Statement { id: ItemId::new(0), kind: StatementKind::Expression(e) })
+    ),
+  char('}'))(text)
+}
+
 fn call_expr(text: &str) -> ParseResult<ExpressionKind> {
   use nom::character::complete::char;
   let parse_call = opt(