Respect operator precedence when printing

examples/test.rs

@@ -1,5 +1,3 @@
-use foliage::format;
-
 fn main() -> Result<(), Box<dyn std::error::Error>>
 {
 	let formulas = "forall XV1 (p(XV1) <-> (exists XU1 (exists X1, X2 (X1 = XU1 and exists N1, N2, N3 (N1 = 0 and N2 = n and N1 <= N3 and N3 <= N2 and X2 = N3) and X1 = X2) and exists X3, X4 (exists N4, N5 (X3 = (N4 * N5) and N4 = XU1 and N5 = XU1) and X4 = n and X3 <= X4) and XV1 = XU1)))
@@ -13,5 +11,16 @@ forall XV2 (q(XV2) <-> (exists XU2 (exists X5 (X5 = XU2 and p(X5)) and exists X6
 		println!("{}", formula);
 	}
 
+	let formulas = "forall XV1 (p(XV1) <-> exists XU1 (exists X1, X2 (X1 = XU1 and exists N1, N2, N3 (N1 = 0 and N2 = n and N1 <= N3 and N3 <= N2 and X2 = N3) and X1 = X2) and exists X3, X4 (exists N4, N5 (X3 = N4 * N5 and N4 = XU1 and N5 = XU1) and X4 = n and X3 <= X4) and XV1 = XU1))
+forall XV2 (q(XV2) <-> exists XU2 (exists X5 (X5 = XU2 and p(X5)) and exists X6 (exists N6, N7 (X6 = N6 + N7 and N6 = XU2 and N7 = 1) and not p(X6)) and XV2 = XU2))";
+
+	let (i, formulas) = foliage::formulas(formulas).unwrap();
+	assert_eq!(i, "");
+
+	for formula in formulas
+	{
+		println!("{}", formula);
+	}
+
 	Ok(())
 }

src/format.rs

@@ -1,3 +1,34 @@
+struct TermDisplay<'term>
+{
+	parent_precedence: u64,
+	term: &'term crate::Term,
+}
+
+struct FormulaDisplay<'formula>
+{
+	parent_precedence: u64,
+	formula: &'formula crate::Formula,
+}
+
+fn display_term<'term>(term: &'term crate::Term, parent_precedence: u64) -> TermDisplay<'term>
+{
+	TermDisplay
+	{
+		parent_precedence,
+		term,
+	}
+}
+
+fn display_formula<'formula>(formula: &'formula crate::Formula, parent_precedence: u64)
+	-> FormulaDisplay<'formula>
+{
+	FormulaDisplay
+	{
+		parent_precedence,
+		formula,
+	}
+}
+
 fn term_precedence(term: &crate::Term) -> u64
 {
 	match term
@@ -51,11 +82,19 @@ impl std::fmt::Display for crate::VariableDeclaration
 	}
 }
 
-impl std::fmt::Debug for crate::Term
+impl<'term> std::fmt::Debug for TermDisplay<'term>
 {
 	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
 	{
-		match *self
+		let precedence = term_precedence(self.term);
+		let requires_parentheses = precedence > self.parent_precedence;
+
+		if requires_parentheses
+		{
+			write!(format, "(")?;
+		}
+
+		match self.term
 		{
 			crate::Term::Infimum => write!(format, "#inf"),
 			crate::Term::Supremum => write!(format, "#sup"),
@@ -63,138 +102,154 @@ impl std::fmt::Debug for crate::Term
 			crate::Term::Symbolic(ref value) => write!(format, "{}", value),
 			crate::Term::String(ref value) => write!(format, "\"{}\"", value),
 			crate::Term::Variable(ref declaration) => write!(format, "{:?}", declaration),
-			crate::Term::Add(ref left, ref right) => write!(format, "({:?} + {:?})", left, right),
+			crate::Term::Add(ref left, ref right) => write!(format, "{:?} + {:?}", display_term(left, precedence), display_term(right, precedence)),
-			crate::Term::Subtract(ref left, ref right) => write!(format, "({:?} - {:?})", left, right),
+			crate::Term::Subtract(ref left, ref right) => write!(format, "{:?} - {:?}", display_term(left, precedence), display_term(right, precedence)),
-			crate::Term::Multiply(ref left, ref right) => write!(format, "({:?} * {:?})", left, right),
+			crate::Term::Multiply(ref left, ref right) => write!(format, "{:?} * {:?}", display_term(left, precedence), display_term(right, precedence)),
-			crate::Term::Negative(ref argument) => write!(format, "-({:?})", argument),
+			crate::Term::Negative(ref argument) => write!(format, "-{:?}", display_term(argument, precedence)),
+		}?;
+
+		if requires_parentheses
+		{
+			write!(format, ")")?;
 		}
+
+		Ok(())
 	}
 }
 
-impl std::fmt::Display for crate::Term
+impl<'term> std::fmt::Display for TermDisplay<'term>
 {
 	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
 	{
-		match *self
+		write!(format, "{:?}", self)
-		{
-			crate::Term::Infimum => write!(format, "#inf"),
-			crate::Term::Supremum => write!(format, "#sup"),
-			crate::Term::Integer(value) => write!(format, "{}", value),
-			crate::Term::Symbolic(ref value) => write!(format, "{}", value),
-			crate::Term::String(ref value) => write!(format, "\"{}\"", value),
-			crate::Term::Variable(ref declaration) => write!(format, "{}", declaration),
-			crate::Term::Add(ref left, ref right) => write!(format, "({} + {})", left, right),
-			crate::Term::Subtract(ref left, ref right) => write!(format, "({} - {})", left, right),
-			crate::Term::Multiply(ref left, ref right) => write!(format, "({} * {})", left, right),
-			crate::Term::Negative(ref argument) => write!(format, "-({})", argument),
 	}
 }
+
+impl<'formula> std::fmt::Debug for FormulaDisplay<'formula>
+{
+	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		let precedence = formula_precedence(self.formula);
+		let requires_parentheses = precedence > self.parent_precedence;
+
+		if requires_parentheses
+		{
+			write!(format, "(")?;
+		}
+
+		match self.formula
+		{
+			crate::Formula::Exists(ref exists) =>
+			{
+				write!(format, "exists")?;
+
+				let mut separator = " ";
+
+				for parameter in &exists.parameters
+				{
+					write!(format, "{}{:?}", separator, parameter)?;
+
+					separator = ", "
+				}
+
+				write!(format, " {:?}", display_formula(&exists.argument, precedence))?;
+			},
+			crate::Formula::ForAll(ref for_all) =>
+			{
+				write!(format, "forall")?;
+
+				let mut separator = " ";
+
+				for parameter in &for_all.parameters
+				{
+					write!(format, "{}{:?}", separator, parameter)?;
+
+					separator = ", "
+				}
+
+				write!(format, " {:?}", display_formula(&for_all.argument, precedence))?;
+			},
+			crate::Formula::Not(ref argument) => write!(format, "not {:?}", display_formula(argument, precedence))?,
+			crate::Formula::And(ref arguments) =>
+			{
+				let mut separator = "";
+
+				for argument in arguments
+				{
+					write!(format, "{}{:?}", separator, display_formula(argument, precedence))?;
+
+					separator = " and "
+				}
+			},
+			crate::Formula::Or(ref arguments) =>
+			{
+				let mut separator = "";
+
+				for argument in arguments
+				{
+					write!(format, "{}{:?}", separator, display_formula(argument, precedence))?;
+
+					separator = " or "
+				}
+			},
+			crate::Formula::Implies(ref left, ref right) => write!(format, "{:?} -> {:?}", display_formula(left, precedence), display_formula(right, precedence))?,
+			crate::Formula::Biconditional(ref left, ref right) => write!(format, "{:?} <-> {:?}", display_formula(left, precedence), display_formula(right, precedence))?,
+			crate::Formula::Less(ref left, ref right) => write!(format, "{:?} < {:?}", display_term(left, 1000), display_term(right, 1000))?,
+			crate::Formula::LessOrEqual(ref left, ref right) => write!(format, "{:?} <= {:?}", display_term(left, 1000), display_term(right, 1000))?,
+			crate::Formula::Greater(ref left, ref right) => write!(format, "{:?} > {:?}", display_term(left, 1000), display_term(right, 1000))?,
+			crate::Formula::GreaterOrEqual(ref left, ref right) => write!(format, "{:?} >= {:?}", display_term(left, 1000), display_term(right, 1000))?,
+			crate::Formula::Equal(ref left, ref right) => write!(format, "{:?} = {:?}", display_term(left, 1000), display_term(right, 1000))?,
+			crate::Formula::NotEqual(ref left, ref right) => write!(format, "{:?} != {:?}", display_term(left, 1000), display_term(right, 1000))?,
+			crate::Formula::Boolean(value) =>
+				match value
+				{
+					true => write!(format, "#true")?,
+					false => write!(format, "#false")?,
+				},
+			crate::Formula::Predicate(ref predicate) =>
+			{
+				write!(format, "{}", predicate.declaration.name)?;
+
+				if !predicate.arguments.is_empty()
+				{
+					write!(format, "(")?;
+
+					let mut separator = "";
+
+					for argument in &predicate.arguments
+					{
+						write!(format, "{}{:?}", separator, display_term(argument, 1000))?;
+
+						separator = ", "
+					}
+
+					write!(format, ")")?;
+				}
+			},
+		}
+
+		if requires_parentheses
+		{
+			write!(format, ")")?;
+		}
+
+		Ok(())
+	}
+}
+
+impl<'formula> std::fmt::Display for FormulaDisplay<'formula>
+{
+	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		write!(format, "{:?}", self)
+	}
 }
 
 impl std::fmt::Debug for crate::Formula
 {
 	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
 	{
-		match *self
+		write!(format, "{:?}", display_formula(&self, 1000))
-		{
-			crate::Formula::Exists(ref exists) =>
-			{
-				write!(format, "exists")?;
-
-				let mut separator = " ";
-
-				for parameter in &exists.parameters
-				{
-					write!(format, "{}{:?}", separator, parameter)?;
-
-					separator = ", "
-				}
-
-				write!(format, " ({:?})", exists.argument)
-			},
-			crate::Formula::ForAll(ref for_all) =>
-			{
-				write!(format, "forall")?;
-
-				let mut separator = " ";
-
-				for parameter in &for_all.parameters
-				{
-					write!(format, "{}{:?}", separator, parameter)?;
-
-					separator = ", "
-				}
-
-				write!(format, " ({:?})", for_all.argument)
-			},
-			crate::Formula::Not(ref argument) => write!(format, "not {:?}", argument),
-			crate::Formula::And(ref arguments) =>
-			{
-				write!(format, "(")?;
-
-				let mut separator = "";
-
-				for argument in arguments
-				{
-					write!(format, "{}{:?}", separator, argument)?;
-
-					separator = " and "
-				}
-
-				write!(format, ")")
-			},
-			crate::Formula::Or(ref arguments) =>
-			{
-				write!(format, "(")?;
-
-				let mut separator = "";
-
-				for argument in arguments
-				{
-					write!(format, "{}{:?}", separator, argument)?;
-
-					separator = " or "
-				}
-
-				write!(format, ")")
-			},
-			crate::Formula::Implies(ref left, ref right) => write!(format, "({:?} -> {:?})", left, right),
-			crate::Formula::Biconditional(ref left, ref right) => write!(format, "({:?} <-> {:?})", left, right),
-			crate::Formula::Less(ref left, ref right) => write!(format, "({:?} < {:?})", left, right),
-			crate::Formula::LessOrEqual(ref left, ref right) => write!(format, "({:?} <= {:?})", left, right),
-			crate::Formula::Greater(ref left, ref right) => write!(format, "({:?} > {:?})", left, right),
-			crate::Formula::GreaterOrEqual(ref left, ref right) => write!(format, "({:?} >= {:?})", left, right),
-			crate::Formula::Equal(ref left, ref right) => write!(format, "({:?} = {:?})", left, right),
-			crate::Formula::NotEqual(ref left, ref right) => write!(format, "({:?} != {:?})", left, right),
-			crate::Formula::Boolean(value) =>
-				match value
-				{
-					true => write!(format, "#true"),
-					false => write!(format, "#false"),
-				},
-			crate::Formula::Predicate(ref predicate) =>
-			{
-				write!(format, "{}", predicate.declaration.name)?;
-
-				if !predicate.arguments.is_empty()
-				{
-					write!(format, "(")?;
-
-					let mut separator = "";
-
-					for argument in &predicate.arguments
-					{
-						write!(format, "{}{:?}", separator, argument)?;
-
-						separator = ", "
-					}
-
-					write!(format, ")")?;
-				}
-
-				Ok(())
-			},
-		}
 	}
 }
 
@@ -202,105 +257,22 @@ impl std::fmt::Display for crate::Formula
 {
 	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
 	{
-		match *self
+		write!(format, "{}", display_formula(&self, 1000))
-		{
-			crate::Formula::Exists(ref exists) =>
-			{
-				write!(format, "exists")?;
-
-				let mut separator = " ";
-
-				for parameter in &exists.parameters
-				{
-					write!(format, "{}{}", separator, parameter)?;
-
-					separator = ", "
-				}
-
-				write!(format, " ({})", exists.argument)
-			},
-			crate::Formula::ForAll(ref for_all) =>
-			{
-				write!(format, "forall")?;
-
-				let mut separator = " ";
-
-				for parameter in &for_all.parameters
-				{
-					write!(format, "{}{}", separator, parameter)?;
-
-					separator = ", "
-				}
-
-				write!(format, " ({})", for_all.argument)
-			},
-			crate::Formula::Not(ref argument) => write!(format, "not {}", argument),
-			crate::Formula::And(ref arguments) =>
-			{
-				write!(format, "(")?;
-
-				let mut separator = "";
-
-				for argument in arguments
-				{
-					write!(format, "{}{}", separator, argument)?;
-
-					separator = " and "
-				}
-
-				write!(format, ")")
-			},
-			crate::Formula::Or(ref arguments) =>
-			{
-				write!(format, "(")?;
-
-				let mut separator = "";
-
-				for argument in arguments
-				{
-					write!(format, "{}{}", separator, argument)?;
-
-					separator = " or "
-				}
-
-				write!(format, ")")
-			},
-			crate::Formula::Implies(ref left, ref right) => write!(format, "({} -> {})", left, right),
-			crate::Formula::Biconditional(ref left, ref right) => write!(format, "({} <-> {})", left, right),
-			crate::Formula::Less(ref left, ref right) => write!(format, "({} < {})", left, right),
-			crate::Formula::LessOrEqual(ref left, ref right) => write!(format, "({} <= {})", left, right),
-			crate::Formula::Greater(ref left, ref right) => write!(format, "({} > {})", left, right),
-			crate::Formula::GreaterOrEqual(ref left, ref right) => write!(format, "({} >= {})", left, right),
-			crate::Formula::Equal(ref left, ref right) => write!(format, "({} = {})", left, right),
-			crate::Formula::NotEqual(ref left, ref right) => write!(format, "({} != {})", left, right),
-			crate::Formula::Boolean(value) =>
-				match value
-				{
-					true => write!(format, "#true"),
-					false => write!(format, "#false"),
-				},
-			crate::Formula::Predicate(ref predicate) =>
-			{
-				write!(format, "{}", predicate.declaration.name)?;
-
-				if !predicate.arguments.is_empty()
-				{
-					write!(format, "(")?;
-
-					let mut separator = "";
-
-					for argument in &predicate.arguments
-					{
-						write!(format, "{}{}", separator, argument)?;
-
-						separator = ", "
-					}
-
-					write!(format, ")")?;
-				}
-
-				Ok(())
-			},
 	}
 }
+
+impl std::fmt::Debug for crate::Term
+{
+	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		write!(format, "{:?}", display_term(&self, 1000))
+	}
+}
+
+impl std::fmt::Display for crate::Term
+{
+	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		write!(format, "{}", display_term(&self, 1000))
+	}
 }