Merge the public parsers in lrgrammar to one

This shrinks the generated code to 1Mb (from 2Mb WITH the cfg approach
in #413) while also removing the cfg'ing itself as that barely reduces the
size. (Thus this supersedes #413)

While this is a bit boilerplatey, I'd say it is worthile. We could
generate this in LALRPOP itself with some work
https://github.com/lalrpop/lalrpop/issues/304#issuecomment-431654594

lalrpop/build.rs

@@ -0,0 +1,58 @@
+use std::env;
+use std::error::Error;
+use std::fs;
+use std::path::{Path, PathBuf};
+use std::process::{exit, Command};
+
+fn main() {
+    if let Err(err) = main_() {
+        eprintln!("{}", err);
+        exit(1);
+    }
+}
+
+fn main_() -> Result<(), Box<Error>> {
+    let grammar_file = "src/parser/lrgrammar.lalrpop";
+    println!(r#"cargo:rerun-if-changed={}"#, grammar_file);
+
+    let out_dir = PathBuf::from(env::var("OUT_DIR").expect("cargo did not set OUT_DIR"));
+
+    fs::create_dir_all(out_dir.join("src/parser"))?;
+
+    let target_dir = if Path::new("target").exists() {
+        Path::new("target")
+    } else {
+        Path::new("../target")
+    };
+
+    let lalrpop_path = target_dir
+        .join("debug/lalrpop")
+        .with_extension(env::consts::EXE_EXTENSION);
+    println!(r#"cargo:rerun-if-changed={}"#, lalrpop_path.display());
+
+    if lalrpop_path.exists() {
+        // If compiling lalrpop itself, enable test parsers
+        if target_dir.exists() {
+            env::set_var("CARGO_FEATURE_TEST", "1");
+            println!(r#"cargo:rustc-cfg=feature="test""#);
+        }
+
+        let copied_grammar = out_dir.join("src/parser/lrgrammar.lalrpop");
+        fs::copy(grammar_file, &copied_grammar)
+            .map_err(|err| format!("Unable to grammar to OUT_DIR: {}", err))?;
+        let status = Command::new(lalrpop_path)
+            .args(&[
+                "--force",
+                "--features",
+                "test",
+                copied_grammar
+                    .to_str()
+                    .expect("grammar path is not valid UTF-8"),
+            ])
+            .status()?;
+        if !status.success() {
+            return Err("Compiling the .lalrpop file failed".into());
+        }
+    }
+    Ok(())
+}

lalrpop/src/lib.rs

@@ -1,57 +1,58 @@
-// Need this for rusty_peg
-#![recursion_limit = "256"]
-// I hate this lint.
-#![allow(unused_parens)]
-// The builtin tests don't cover the CLI and so forth, and it's just
-// too darn annoying to try and make them do so.
-#![cfg_attr(test, allow(dead_code))]
-
-extern crate ascii_canvas;
-extern crate atty;
-extern crate bit_set;
-extern crate diff;
-extern crate ena;
-extern crate itertools;
-extern crate lalrpop_util;
-extern crate petgraph;
-extern crate regex;
-extern crate regex_syntax;
-extern crate sha2;
-extern crate string_cache;
-extern crate term;
-extern crate unicode_xid;
-
-#[cfg(test)]
-extern crate rand;
-
-// hoist the modules that define macros up earlier
-#[macro_use]
-mod rust;
-#[macro_use]
-mod log;
-
-mod api;
-mod build;
-mod collections;
-mod file_text;
-mod grammar;
-mod kernel_set;
-mod lexer;
-mod lr1;
-mod message;
-mod normalize;
-mod parser;
-mod session;
-mod tls;
-mod tok;
-mod util;
-
-#[cfg(test)]
-mod generate;
-#[cfg(test)]
-mod test_util;
-
-pub use api::process_root;
-pub use api::process_root_unconditionally;
-pub use api::Configuration;
-use ascii_canvas::style;
+// Need this for rusty_peg
+#![recursion_limit = "256"]
+// I hate this lint.
+#![allow(unused_parens)]
+// The builtin tests don't cover the CLI and so forth, and it's just
+// too darn annoying to try and make them do so.
+#![cfg_attr(test, allow(dead_code))]
+
+extern crate ascii_canvas;
+extern crate atty;
+extern crate bit_set;
+extern crate diff;
+extern crate ena;
+extern crate itertools;
+#[cfg_attr(any(feature = "test", test), macro_use)]
+extern crate lalrpop_util;
+extern crate petgraph;
+extern crate regex;
+extern crate regex_syntax;
+extern crate sha2;
+extern crate string_cache;
+extern crate term;
+extern crate unicode_xid;
+
+#[cfg(test)]
+extern crate rand;
+
+// hoist the modules that define macros up earlier
+#[macro_use]
+mod rust;
+#[macro_use]
+mod log;
+
+mod api;
+mod build;
+mod collections;
+mod file_text;
+mod grammar;
+mod kernel_set;
+mod lexer;
+mod lr1;
+mod message;
+mod normalize;
+mod parser;
+mod session;
+mod tls;
+mod tok;
+mod util;
+
+#[cfg(test)]
+mod generate;
+#[cfg(test)]
+mod test_util;
+
+pub use api::process_root;
+pub use api::process_root_unconditionally;
+pub use api::Configuration;
+use ascii_canvas::style;

lalrpop/src/parser/lrgrammar.lalrpop

@@ -6,9 +6,19 @@ use tok::{self, Tok};
 use util::strip;
 use lalrpop_util::ParseError;
 
+use super::Top;
+
 grammar<'input>(text: &'input str);
 
-pub Grammar: Grammar =
+pub Top: Top = {
+    "StartGrammar" <Grammar> => Top::Grammar(<>),
+    "StartPattern" <Pattern> => Top::Pattern(<>),
+    "StartMatchMapping" <MatchMapping> => Top::MatchMapping(<>),
+    "StartTypeRef" <TypeRef> => Top::TypeRef(<>),
+    "StartGrammarWhereClauses" <GrammarWhereClauses> => Top::GrammarWhereClauses(<>),
+};
+
+Grammar: Grammar =
     <module_attributes:ShebangAttribute*>
     <uses:Use*>
     <annotations:Annotation*>
@@ -36,7 +46,7 @@ TypeParameter: TypeParameter = {
     <l:Id> => TypeParameter::Id(l)
 };
 
-pub GrammarWhereClauses: Vec<WhereClause<TypeRef>> =
+GrammarWhereClauses: Vec<WhereClause<TypeRef>> =
     "where" <Comma<GrammarWhereClause>>;
 
 GrammarWhereClause: WhereClause<TypeRef> = {
@@ -226,7 +236,7 @@ SymbolKind1: SymbolKind = {
         SymbolKind::Error,
 };
 
-pub TypeRef: TypeRef = {
+TypeRef: TypeRef = {
     "(" <Comma<TypeRef>> ")" =>
         TypeRef::Tuple(<>),
 
@@ -299,7 +309,7 @@ MatchItem: MatchItem = {
 
 MatchSymbol = QuotedLiteral;
 
-pub MatchMapping = Terminal;
+MatchMapping = Terminal;
 
 EnumToken: EnumToken =
     "enum" <lo:@L> <t:TypeRef> <hi:@R> "{"
@@ -327,7 +337,7 @@ Conversion: Conversion =
                         to: pattern })
     };
 
-pub Pattern: Pattern<TypeRef> =
+Pattern: Pattern<TypeRef> =
     <lo:@L> <k:PatternKind> <hi:@R> => Pattern { span: Span(lo, hi), kind: k };
 
 PatternKind: PatternKind<TypeRef> = {
@@ -472,5 +482,11 @@ extern {
         "*" => Tok::Star,
         "~~" => Tok::TildeTilde,
         "_" => Tok::Underscore,
+
+        "StartGrammar" => Tok::StartGrammar,
+        "StartPattern" => Tok::StartPattern,
+        "StartMatchMapping" => Tok::StartMatchMapping,
+        "StartTypeRef" => Tok::StartTypeRef,
+        "StartGrammarWhereClauses" => Tok::StartGrammarWhereClauses,
     }
 }

lalrpop/src/parser/mod.rs

@@ -1,54 +1,84 @@
-use grammar::parse_tree::*;
-use grammar::pattern::*;
-use lalrpop_util;
-use tok;
-
-#[allow(dead_code)]
-mod lrgrammar;
-
-#[cfg(test)]
-mod test;
-
-pub type ParseError<'input> = lalrpop_util::ParseError<usize, tok::Tok<'input>, tok::Error>;
-
-pub fn parse_grammar<'input>(input: &'input str) -> Result<Grammar, ParseError<'input>> {
-    let tokenizer = tok::Tokenizer::new(input, 0);
-    let mut grammar = try!(lrgrammar::GrammarParser::new().parse(input, tokenizer));
-
-    // find a unique prefix that does not appear anywhere in the input
-    while input.contains(&grammar.prefix) {
-        grammar.prefix.push('_');
-    }
-
-    Ok(grammar)
-}
-
-fn parse_pattern<'input>(
-    input: &'input str,
-    offset: usize,
-) -> Result<Pattern<TypeRef>, ParseError<'input>> {
-    let tokenizer = tok::Tokenizer::new(input, offset);
-    lrgrammar::PatternParser::new().parse(input, tokenizer)
-}
-
-fn parse_match_mapping<'input>(
-    input: &'input str,
-    offset: usize,
-) -> Result<MatchMapping, ParseError<'input>> {
-    let tokenizer = tok::Tokenizer::new(input, offset);
-    lrgrammar::MatchMappingParser::new().parse(input, tokenizer)
-}
-
-#[cfg(test)]
-pub fn parse_type_ref<'input>(input: &'input str) -> Result<TypeRef, ParseError<'input>> {
-    let tokenizer = tok::Tokenizer::new(input, 0);
-    lrgrammar::TypeRefParser::new().parse(input, tokenizer)
-}
-
-#[cfg(test)]
-pub fn parse_where_clauses<'input>(
-    input: &'input str,
-) -> Result<Vec<WhereClause<TypeRef>>, ParseError<'input>> {
-    let tokenizer = tok::Tokenizer::new(input, 0);
-    lrgrammar::GrammarWhereClausesParser::new().parse(input, tokenizer)
-}
+use std::iter;
+
+use grammar::parse_tree::*;
+use grammar::pattern::*;
+use lalrpop_util;
+use tok;
+
+#[cfg(not(any(feature = "test", test)))]
+#[allow(dead_code)]
+mod lrgrammar;
+
+#[cfg(any(feature = "test", test))]
+lalrpop_mod!(
+    // ---------------------------------------------------------------------------------------
+    // NOTE: Run `cargo build -p lalrpop` once before running `cargo test` to create this file
+    // ---------------------------------------------------------------------------------------
+    #[allow(dead_code)]
+    lrgrammar,
+    "/src/parser/lrgrammar.rs"
+);
+
+#[cfg(test)]
+mod test;
+
+pub enum Top {
+    Grammar(Grammar),
+    Pattern(Pattern<TypeRef>),
+    MatchMapping(TerminalString),
+    TypeRef(TypeRef),
+    GrammarWhereClauses(Vec<WhereClause<TypeRef>>),
+}
+
+pub type ParseError<'input> = lalrpop_util::ParseError<usize, tok::Tok<'input>, tok::Error>;
+
+macro_rules! parser {
+    ($input: expr, $offset: expr, $pat: ident, $tok: ident) => {{
+        let input = $input;
+        let tokenizer =
+            iter::once(Ok((0, tok::Tok::$tok, 0))).chain(tok::Tokenizer::new(input, $offset));
+        lrgrammar::TopParser::new()
+            .parse(input, tokenizer)
+            .map(|top| match top {
+                Top::$pat(x) => x,
+                _ => unreachable!(),
+            })
+    }};
+}
+
+pub fn parse_grammar<'input>(input: &'input str) -> Result<Grammar, ParseError<'input>> {
+    let mut grammar = try!(parser!(input, 0, Grammar, StartGrammar));
+
+    // find a unique prefix that does not appear anywhere in the input
+    while input.contains(&grammar.prefix) {
+        grammar.prefix.push('_');
+    }
+
+    Ok(grammar)
+}
+
+fn parse_pattern<'input>(
+    input: &'input str,
+    offset: usize,
+) -> Result<Pattern<TypeRef>, ParseError<'input>> {
+    parser!(input, offset, Pattern, StartPattern)
+}
+
+fn parse_match_mapping<'input>(
+    input: &'input str,
+    offset: usize,
+) -> Result<MatchMapping, ParseError<'input>> {
+    parser!(input, offset, MatchMapping, StartMatchMapping)
+}
+
+#[cfg(test)]
+pub fn parse_type_ref<'input>(input: &'input str) -> Result<TypeRef, ParseError<'input>> {
+    parser!(input, 0, TypeRef, StartTypeRef)
+}
+
+#[cfg(test)]
+pub fn parse_where_clauses<'input>(
+    input: &'input str,
+) -> Result<Vec<WhereClause<TypeRef>>, ParseError<'input>> {
+    parser!(input, 0, GrammarWhereClauses, StartGrammarWhereClauses)
+}

lalrpop/src/tok/mod.rs

@@ -97,6 +97,15 @@ pub enum Tok<'input> {
     Underscore,
     Bang,
     ShebangAttribute(&'input str), // #![...]
+
+    // Dummy tokens for parser sharing
+    StartGrammar,
+    StartPattern,
+    StartMatchMapping,
+    #[allow(dead_code)]
+    StartGrammarWhereClauses,
+    #[allow(dead_code)]
+    StartTypeRef,
 }
 
 pub struct Tokenizer<'input> {