From ad6d8e182b26a13fd4a6816a1be6e2ac3a2664d1 Mon Sep 17 00:00:00 2001
From: Chris Mounce <christophermounce@gmail.com>
Date: Fri, 30 May 2025 00:17:24 -0700
Subject: [PATCH] Add case-insensitive matching

---
 peg_macro/src/lib.rs | 29 +++++++++++++++++++++++++----
 src/peg/peg.rs       | 31 +++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/peg_macro/src/lib.rs b/peg_macro/src/lib.rs
index d2ea7fc..7a62083 100644
--- a/peg_macro/src/lib.rs
+++ b/peg_macro/src/lib.rs
@@ -25,11 +25,13 @@ enum Term {
     Choice(Vec<Term>),
     EOI,
     Literal(String),
+    LiteralI(String),
     NegLookahead(Box<Term>),
     Optional(Box<Term>),
     Plus(Box<Term>),
     PosLookahead(Box<Term>),
     Range(RangeInclusive<char>),
+    RangeI(RangeInclusive<char>),
     Rule(Ident),
     Sequence(Vec<Term>),
     Star(Box<Term>),
@@ -60,10 +62,15 @@ impl Parse for Rule {
 impl Parse for Term {
     fn parse(input: ParseStream) -> syn::Result<Self> {
         fn parse_range(input: ParseStream) -> syn::Result<Term> {
-            let start = input.parse::<LitChar>()?.value();
+            let start_lit = input.parse::<LitChar>()?;
             input.parse::<Token![..]>()?;
-            let end = input.parse::<LitChar>()?.value();
-            Ok(Term::Range(start..=end))
+            let end_lit = input.parse::<LitChar>()?;
+            let range = start_lit.value()..=end_lit.value();
+            if end_lit.suffix() == "i" {
+                Ok(Term::RangeI(range))
+            } else {
+                Ok(Term::Range(range))
+            }
         }
 
         fn parse_atom(input: ParseStream) -> syn::Result<Term> {
@@ -77,7 +84,12 @@ impl Parse for Term {
                     input.parse().map(Term::Rule)
                 }
             } else if look.peek(LitStr) {
-                input.parse::<LitStr>().map(|x| Term::Literal(x.value()))
+                let lit = input.parse::<LitStr>()?;
+                if lit.suffix() == "i" {
+                    Ok(Term::LiteralI(lit.value()))
+                } else {
+                    Ok(Term::Literal(lit.value()))
+                }
             } else if look.peek(LitChar) {
                 parse_range(input)
             } else if look.peek(syn::token::Paren) {
@@ -159,6 +171,9 @@ impl Term {
             Term::Literal(lit_str) => quote! {
                 p.literal(#lit_str)
             },
+            Term::LiteralI(lit_str) => quote! {
+                p.literal_i(#lit_str)
+            },
             Term::Sequence(terms) => {
                 let expr = terms
                     .iter()
@@ -218,6 +233,12 @@ impl Term {
                     p.range(#lo..=#hi)
                 }
             }
+            Term::RangeI(range) => {
+                let (lo, hi) = (range.start(), range.end());
+                quote! {
+                    p.range_i(#lo..=#hi)
+                }
+            }
             Term::NegLookahead(term) => {
                 let code = term.generate_code();
                 quote! {
diff --git a/src/peg/peg.rs b/src/peg/peg.rs
index ce8be35..bd24e63 100644
--- a/src/peg/peg.rs
+++ b/src/peg/peg.rs
@@ -36,6 +36,15 @@ impl ParseState {
         }
     }
 
+    pub fn literal_i(&mut self, s: &str) -> bool {
+        if self.input[self.offset..(self.offset + s.len())].eq_ignore_ascii_case(s) {
+            self.offset += s.len();
+            true
+        } else {
+            false
+        }
+    }
+
     pub fn range(&mut self, r: RangeInclusive<char>) -> bool {
         if let Some(next) = self.input[self.offset..].chars().next() {
             if r.contains(&next) {
@@ -46,6 +55,16 @@ impl ParseState {
         false
     }
 
+    pub fn range_i(&mut self, r: RangeInclusive<char>) -> bool {
+        if let Some(next) = self.input[self.offset..].chars().next() {
+            if r.contains(&next.to_ascii_lowercase()) || r.contains(&next.to_ascii_uppercase()) {
+                self.offset += next.len_utf8();
+                return true;
+            }
+        }
+        false
+    }
+
     pub fn any(&mut self) -> bool {
         if let Some(c) = self.input[self.offset..].chars().next() {
             self.offset += c.len_utf8();
@@ -85,6 +104,8 @@ mod tests {
 
         dq = "\"";
         quoted = dq ("\\" ANY / !dq ANY)* dq;
+
+        case_sensitivity = "Strict " ('a'..'z')+ ", loose "i ('a'..'z'i)+;
     }
 
     fn parse<T: Fn(&mut ParseState) -> bool>(rule: T, s: &str) -> bool {
@@ -163,4 +184,14 @@ mod tests {
         assert!(!parse(quoted, r#""foo " bar""#));
         assert!(!parse(quoted, r#""false end \""#));
     }
+
+    #[test]
+    fn test_i_suffix() {
+        assert!(parse(case_sensitivity, "Strict abc, loose xyz"));
+        assert!(!parse(case_sensitivity, "STRICT abc, loose xyz"));
+        assert!(!parse(case_sensitivity, "Strict ABC, loose xyz"));
+        assert!(parse(case_sensitivity, "Strict abc, LOOSE xyz"));
+        assert!(parse(case_sensitivity, "Strict abc, loose XYZ"));
+        assert!(parse(case_sensitivity, "Strict abc, LoOsE XyZ"));
+    }
 }