use crate::syntax::*; use itertools::Itertools; use std::fmt::{self, Display}; // There is a one-to-one correspondence between the formatter and the grammar. Each phase is // named after a corresponding grammar group, and the structure of the formatter reflects // the relationship between the corresponding grammar rules. This leads to the nice property // of automatically getting all the parentheses and precedences right. #[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)] enum PrintPhase { Base, Operator, BinOp(ast::BinOp), App, Import, Primitive, } // Wraps an Expr with a phase, so that phase selection can be done separate from the actual // printing. #[derive(Clone)] struct PhasedExpr<'a>(&'a Expr, PrintPhase); impl<'a> PhasedExpr<'a> { fn phase(self, phase: PrintPhase) -> PhasedExpr<'a> { PhasedExpr(self.0, phase) } } impl UnspannedExpr { // Annotate subexpressions with the appropriate phase, defaulting to Base fn annotate_with_phases<'a>(&'a self) -> ExprKind> { use crate::syntax::ExprKind::*; use PrintPhase::*; let with_base = self.map_ref(|e| PhasedExpr(e, Base)); match with_base { Pi(a, b, c) => { if &String::from(&a) == "_" { Pi(a, b.phase(Operator), c) } else { Pi(a, b, c) } } Merge(a, b, c) => Merge( a.phase(PrintPhase::Import), b.phase(PrintPhase::Import), c.map(|x| x.phase(PrintPhase::App)), ), ToMap(a, b) => ToMap( a.phase(PrintPhase::Import), b.map(|x| x.phase(PrintPhase::App)), ), Annot(a, b) => Annot(a.phase(Operator), b), ExprKind::BinOp(op, a, b) => ExprKind::BinOp( op, a.phase(PrintPhase::BinOp(op)), b.phase(PrintPhase::BinOp(op)), ), SomeLit(e) => SomeLit(e.phase(PrintPhase::Import)), ExprKind::App(f, a) => ExprKind::App( f.phase(PrintPhase::Import), a.phase(PrintPhase::Import), ), Field(a, b) => Field(a.phase(Primitive), b), Projection(e, ls) => Projection(e.phase(Primitive), ls), ProjectionByExpr(a, b) => ProjectionByExpr(a.phase(Primitive), b), Completion(a, b) => { Completion(a.phase(Primitive), b.phase(Primitive)) } e => e, } } fn fmt_phase( &self, f: &mut fmt::Formatter, phase: PrintPhase, ) -> Result<(), fmt::Error> { use crate::syntax::ExprKind::*; let needs_paren = match self { Lam(_, _, _) | BoolIf(_, _, _) | Pi(_, _, _) | Let(_, _, _, _) | EmptyListLit(_) | NEListLit(_) | SomeLit(_) | Merge(_, _, _) | ToMap(_, _) | Annot(_, _) => phase > PrintPhase::Base, // Precedence is magically handled by the ordering of BinOps. ExprKind::BinOp(op, _, _) => phase > PrintPhase::BinOp(*op), ExprKind::App(_, _) => phase > PrintPhase::App, Field(_, _) | Projection(_, _) | ProjectionByExpr(_, _) | Completion(_, _) => phase > PrintPhase::Import, _ => false, }; if needs_paren { f.write_str("(")?; } self.annotate_with_phases().fmt(f)?; if needs_paren { f.write_str(")")?; } Ok(()) } } fn fmt_list( open: &str, sep: &str, close: &str, it: I, f: &mut fmt::Formatter, func: F, ) -> Result<(), fmt::Error> where I: IntoIterator, F: Fn(T, &mut fmt::Formatter) -> Result<(), fmt::Error>, { f.write_str(open)?; for (i, x) in it.into_iter().enumerate() { if i > 0 { f.write_str(sep)?; } func(x, f)?; } f.write_str(close) } /// Generic instance that delegates to subexpressions impl Display for ExprKind { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { use crate::syntax::ExprKind::*; match self { Lam(a, b, c) => { write!(f, "λ({} : {}) → {}", a, b, c)?; } BoolIf(a, b, c) => { write!(f, "if {} then {} else {}", a, b, c)?; } Pi(a, b, c) if &String::from(a) == "_" => { write!(f, "{} → {}", b, c)?; } Pi(a, b, c) => { write!(f, "∀({} : {}) → {}", a, b, c)?; } Let(a, b, c, d) => { write!(f, "let {}", a)?; if let Some(b) = b { write!(f, " : {}", b)?; } write!(f, " = {} in {}", c, d)?; } EmptyListLit(t) => { write!(f, "[] : {}", t)?; } NEListLit(es) => { fmt_list("[", ", ", "]", es, f, Display::fmt)?; } SomeLit(e) => { write!(f, "Some {}", e)?; } Merge(a, b, c) => { write!(f, "merge {} {}", a, b)?; if let Some(c) = c { write!(f, " : {}", c)?; } } ToMap(a, b) => { write!(f, "toMap {}", a)?; if let Some(b) = b { write!(f, " : {}", b)?; } } Annot(a, b) => { write!(f, "{} : {}", a, b)?; } Assert(a) => { write!(f, "assert : {}", a)?; } ExprKind::BinOp(op, a, b) => { write!(f, "{} {} {}", a, op, b)?; } ExprKind::App(a, b) => { write!(f, "{} {}", a, b)?; } Field(a, b) => { write!(f, "{}.{}", a, b)?; } Var(a) => a.fmt(f)?, Const(k) => k.fmt(f)?, Builtin(v) => v.fmt(f)?, Lit(a) => a.fmt(f)?, TextLit(a) => a.fmt(f)?, RecordType(a) if a.is_empty() => f.write_str("{}")?, RecordType(a) => fmt_list("{ ", ", ", " }", a, f, |(k, t), f| { write!(f, "{} : {}", k, t) })?, RecordLit(a) if a.is_empty() => f.write_str("{=}")?, RecordLit(a) => fmt_list("{ ", ", ", " }", a, f, |(k, v), f| { write!(f, "{} = {}", k, v) })?, UnionType(a) => fmt_list("< ", " | ", " >", a, f, |(k, v), f| { write!(f, "{}", k)?; if let Some(v) = v { write!(f, ": {}", v)?; } Ok(()) })?, Projection(e, ls) => { write!(f, "{}.", e)?; fmt_list("{ ", ", ", " }", ls, f, Display::fmt)?; } ProjectionByExpr(a, b) => { write!(f, "{}.({})", a, b)?; } Completion(a, b) => { write!(f, "{}::{}", a, b)?; } Import(a) => a.fmt(f)?, } Ok(()) } } impl Display for Expr { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { self.kind().fmt_phase(f, PrintPhase::Base) } } impl Display for LitKind { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { use LitKind::*; match self { Bool(true) => f.write_str("True")?, Bool(false) => f.write_str("False")?, Natural(a) => a.fmt(f)?, Integer(a) if *a >= 0 => { f.write_str("+")?; a.fmt(f)?; } Integer(a) => a.fmt(f)?, Double(a) => a.fmt(f)?, } Ok(()) } } impl<'a> Display for PhasedExpr<'a> { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { self.0.as_ref().fmt_phase(f, self.1) } } impl Display for InterpolatedText { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { f.write_str("\"")?; for x in self.iter() { match x { InterpolatedTextContents::Text(a) => { for c in a.chars() { match c { '\\' => f.write_str("\\\\"), '"' => f.write_str("\\\""), '$' => f.write_str("\\u0024"), '\u{0008}' => f.write_str("\\b"), '\u{000C}' => f.write_str("\\f"), '\n' => f.write_str("\\n"), '\r' => f.write_str("\\r"), '\t' => f.write_str("\\t"), '\u{0000}'..='\u{001F}' => { // Escape to an explicit "\u{XXXX}" form let escaped: String = c.escape_default().collect(); // Print as "\uXXXX" write!( f, "\\u{:0>4}", &escaped[3..escaped.len() - 1] ) } c => write!(f, "{}", c), }?; } } InterpolatedTextContents::Expr(e) => { f.write_str("${ ")?; e.fmt(f)?; f.write_str(" }")?; } } } f.write_str("\"")?; Ok(()) } } impl Display for Const { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { ::fmt(self, f) } } impl Display for BinOp { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { use crate::syntax::BinOp::*; f.write_str(match self { BoolOr => "||", TextAppend => "++", NaturalPlus => "+", BoolAnd => "&&", RecursiveRecordMerge => "∧", NaturalTimes => "*", BoolEQ => "==", BoolNE => "!=", RecursiveRecordTypeMerge => "⩓", ImportAlt => "?", RightBiasedRecordMerge => "⫽", ListAppend => "#", Equivalence => "≡", }) } } impl Display for NaiveDouble { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { let v = f64::from(*self); if v == std::f64::INFINITY { f.write_str("Infinity") } else if v == std::f64::NEG_INFINITY { f.write_str("-Infinity") } else if v.is_nan() { f.write_str("NaN") } else if v == 0.0 && v.is_sign_negative() { f.write_str("-0.0") } else { let s = format!("{}", v); if s.contains('e') || s.contains('.') { f.write_str(&s) } else { write!(f, "{}.0", s) } } } } impl Display for Label { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { // TODO: distinguish between reserved and nonreserved locations for quoting builtins let s = String::from(self); let is_reserved = match s.as_str() { "let" | "in" | "if" | "then" | "else" | "Type" | "Kind" | "Sort" | "True" | "False" => true, _ => crate::syntax::Builtin::parse(&s).is_some(), }; if !is_reserved && s.chars().all(|c| c.is_ascii_alphanumeric()) { write!(f, "{}", s) } else { write!(f, "`{}`", s) } } } impl Display for Hash { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { match self { Hash::SHA256(hash) => write!(f, "sha256:{}", hex::encode(hash)), } } } impl Display for Import { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { use FilePrefix::*; use ImportLocation::*; use ImportMode::*; let quote_if_needed = |s: &str| -> String { if s.chars().all(|c| c.is_ascii_alphanumeric()) { s.to_string() } else { format!("\"{}\"", s) } }; match &self.location { Local(prefix, path) => { let prefix = match prefix { Here => ".", Parent => "..", Home => "~", Absolute => "", }; write!(f, "{}/", prefix)?; let path: String = path .file_path .iter() .map(|c| quote_if_needed(&*c)) .join("/"); f.write_str(&path)?; } Remote(url) => { write!(f, "{}://{}/", url.scheme, url.authority)?; let path: String = url.path.file_path.iter().join("/"); f.write_str(&path)?; if let Some(q) = &url.query { write!(f, "?{}", q)? } if let Some(h) = &url.headers { write!(f, " using ({})", h)? } } Env(s) => { write!(f, "env:")?; if s.chars().all(|c| c.is_ascii_alphanumeric()) { write!(f, "{}", s)?; } else { write!(f, "\"")?; for c in s.chars() { match c { '"' => f.write_str("\\\"")?, '\\' => f.write_str("\\\\")?, '\u{0007}' => f.write_str("\\a")?, '\u{0008}' => f.write_str("\\b")?, '\u{000C}' => f.write_str("\\f")?, '\n' => f.write_str("\\n")?, '\r' => f.write_str("\\r")?, '\t' => f.write_str("\\t")?, '\u{000B}' => f.write_str("\\v")?, _ => write!(f, "{}", c)?, } } write!(f, "\"")?; } } Missing => { write!(f, "missing")?; } } if let Some(hash) = &self.hash { write!(f, " ")?; hash.fmt(f)?; } match self.mode { Code => {} RawText => write!(f, " as Text")?, Location => write!(f, " as Location")?, } Ok(()) } } impl Display for Builtin { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { use crate::syntax::Builtin::*; f.write_str(match *self { Bool => "Bool", Natural => "Natural", Integer => "Integer", Double => "Double", Text => "Text", List => "List", Optional => "Optional", OptionalNone => "None", NaturalBuild => "Natural/build", NaturalFold => "Natural/fold", NaturalIsZero => "Natural/isZero", NaturalEven => "Natural/even", NaturalOdd => "Natural/odd", NaturalToInteger => "Natural/toInteger", NaturalShow => "Natural/show", NaturalSubtract => "Natural/subtract", IntegerToDouble => "Integer/toDouble", IntegerNegate => "Integer/negate", IntegerClamp => "Integer/clamp", IntegerShow => "Integer/show", DoubleShow => "Double/show", ListBuild => "List/build", ListFold => "List/fold", ListLength => "List/length", ListHead => "List/head", ListLast => "List/last", ListIndexed => "List/indexed", ListReverse => "List/reverse", OptionalFold => "Optional/fold", OptionalBuild => "Optional/build", TextShow => "Text/show", }) } } impl Display for Scheme { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { use crate::syntax::Scheme::*; f.write_str(match *self { HTTP => "http", HTTPS => "https", }) } } impl Display for V { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { let V(x, n) = self; x.fmt(f)?; if *n != 0 { write!(f, "@{}", n)?; } Ok(()) } }