1 files changed, 155 insertions, 0 deletions
diff --git a/crates/mozart-console-macros/src/codegen.rs b/crates/mozart-console-macros/src/codegen.rs
new file mode 100644
index 0000000..11e37f9
--- /dev/null
+++ b/crates/mozart-console-macros/src/codegen.rs
@@ -0,0 +1,155 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::Expr;
+use syn::punctuated::Punctuated;
+
+use crate::parser::Segment;
+
+/// Returns true if the string contains any format placeholders (`{}`, `{name}`, `{0}`, `{:<10}`, etc.)
+/// but not escaped braces `{{` or `}}`.
+fn has_placeholders(s: &str) -> bool {
+    let mut chars = s.chars().peekable();
+    while let Some(ch) = chars.next() {
+        if ch == '{' {
+            match chars.peek() {
+                Some('{') => {
+                    chars.next(); // skip escaped
+                }
+                _ => return true,
+            }
+        } else if ch == '}' && chars.peek() == Some(&'}') {
+            chars.next(); // skip escaped
+        }
+    }
+    false
+}
+
+/// Count implicit positional placeholders (`{}` and `{:spec}`) in a format string.
+/// Named (`{name}`) and numbered (`{0}`) placeholders are NOT counted
+/// since they don't consume positional arguments.
+fn count_positional_placeholders(s: &str) -> usize {
+    let mut count = 0;
+    let mut chars = s.chars().peekable();
+    while let Some(ch) = chars.next() {
+        if ch == '{' {
+            match chars.peek() {
+                Some('{') => {
+                    chars.next(); // escaped
+                }
+                Some('}') => {
+                    // `{}`  — implicit positional
+                    count += 1;
+                    chars.next();
+                }
+                Some(':') => {
+                    // `{:spec}` — implicit positional with format spec
+                    count += 1;
+                    for c in chars.by_ref() {
+                        if c == '}' {
+                            break;
+                        }
+                    }
+                }
+                Some(c) if c.is_ascii_digit() => {
+                    // `{0}`, `{0:spec}` — explicit positional, skip
+                    for c in chars.by_ref() {
+                        if c == '}' {
+                            break;
+                        }
+                    }
+                }
+                _ => {
+                    // `{name}` or `{name:spec}` — named, skip
+                    for c in chars.by_ref() {
+                        if c == '}' {
+                            break;
+                        }
+                    }
+                }
+            }
+        } else if ch == '}' && chars.peek() == Some(&'}') {
+            chars.next();
+        }
+    }
+    count
+}
+
+pub fn generate(
+    segments: &[Segment],
+    extra_args: &Punctuated<Expr, syn::Token![,]>,
+) -> TokenStream {
+    // Single segment: pass all extra args
+    if segments.len() == 1 {
+        return generate_single(&segments[0], extra_args);
+    }
+
+    // Multiple segments: distribute positional args across segments
+    let mut pos = 0usize;
+    let mut seg_bindings = Vec::new();
+    let mut seg_idents = Vec::new();
+
+    for (i, segment) in segments.iter().enumerate() {
+        let content = segment_content(segment);
+        let n = count_positional_placeholders(content);
+        let end = (pos + n).min(extra_args.len());
+        let slice: Punctuated<Expr, syn::Token![,]> = extra_args
+            .iter()
+            .skip(pos)
+            .take(end - pos)
+            .cloned()
+            .collect();
+        pos = end;
+
+        let ident = quote::format_ident!("__seg{}", i);
+        let expr = generate_single(segment, &slice);
+        seg_bindings.push(quote! { let #ident = #expr; });
+        seg_idents.push(ident);
+    }
+
+    // Build a format string with one `{}` per segment
+    let fmt_str = seg_idents.iter().map(|_| "{}").collect::<Vec<_>>().join("");
+
+    quote! {
+        {
+            #(#seg_bindings)*
+            ::std::format!(#fmt_str, #(#seg_idents),*)
+        }
+    }
+}
+
+fn segment_content(segment: &Segment) -> &str {
+    match segment {
+        Segment::Plain(s) => s,
+        Segment::Tagged { content, .. } => content,
+    }
+}
+
+fn generate_single(segment: &Segment, args: &Punctuated<Expr, syn::Token![,]>) -> TokenStream {
+    match segment {
+        Segment::Plain(text) => {
+            if has_placeholders(text) {
+                let lit = proc_macro2::Literal::string(text);
+                quote! { ::std::format!(#lit, #args) }
+            } else {
+                quote! { ::std::string::String::from(#text) }
+            }
+        }
+        Segment::Tagged { tag, content } => {
+            let func = quote::format_ident!("{}", tag);
+            if has_placeholders(content) {
+                let lit = proc_macro2::Literal::string(content);
+                quote! {
+                    ::std::string::ToString::to_string(
+                        &::mozart_core::console::#func(&::std::format!(#lit, #args))
+                    )
+                }
+            } else {
+                quote! {
+                    ::std::string::ToString::to_string(
+                        &::mozart_core::console::#func(#content)
+                    )
+                }
+            }
+        }
+    }
+}