From dcc28a6ec7ff6bf9838b742a7ca8d711f9dc244b Mon Sep 17 00:00:00 2001
From: Tobie Morgan Hitchcock <tobie@abcum.com>
Date: Fri, 9 Dec 2022 16:02:36 +0000
Subject: [PATCH] Allow `SELECT` statements to `START AT 0`

Closes #1516
---
 lib/src/sql/number.rs      | 24 ++++++++++++++++++++++++
 lib/src/sql/start.rs       |  2 +-
 lib/src/sql/value/value.rs | 12 ++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/lib/src/sql/number.rs b/lib/src/sql/number.rs
index b8d697a7..ff070800 100644
--- a/lib/src/sql/number.rs
+++ b/lib/src/sql/number.rs
@@ -235,6 +235,30 @@ impl Number {
 		}
 	}
 
+	pub fn is_negative(&self) -> bool {
+		match self {
+			Number::Int(v) => v < &0,
+			Number::Float(v) => v < &0.0,
+			Number::Decimal(v) => v < &BigDecimal::from(0),
+		}
+	}
+
+	pub fn is_zero_or_positive(&self) -> bool {
+		match self {
+			Number::Int(v) => v >= &0,
+			Number::Float(v) => v >= &0.0,
+			Number::Decimal(v) => v >= &BigDecimal::from(0),
+		}
+	}
+
+	pub fn is_zero_or_negative(&self) -> bool {
+		match self {
+			Number::Int(v) => v <= &0,
+			Number::Float(v) => v <= &0.0,
+			Number::Decimal(v) => v <= &BigDecimal::from(0),
+		}
+	}
+
 	// -----------------------------------
 	// Simple conversion of number
 	// -----------------------------------
diff --git a/lib/src/sql/start.rs b/lib/src/sql/start.rs
index 8c4157c6..6bd92ba9 100644
--- a/lib/src/sql/start.rs
+++ b/lib/src/sql/start.rs
@@ -23,7 +23,7 @@ impl Start {
 		doc: Option<&Value>,
 	) -> Result<usize, Error> {
 		match self.0.compute(ctx, opt, txn, doc).await {
-			Ok(v) if v.is_integer() && v.is_positive() => Ok(v.as_usize()),
+			Ok(v) if v.is_integer() && v.is_zero_or_positive() => Ok(v.as_usize()),
 			Ok(v) => Err(Error::InvalidStart {
 				value: v.as_string(),
 			}),
diff --git a/lib/src/sql/value/value.rs b/lib/src/sql/value/value.rs
index aae2559f..3535d5a4 100644
--- a/lib/src/sql/value/value.rs
+++ b/lib/src/sql/value/value.rs
@@ -698,6 +698,18 @@ impl Value {
 		matches!(self, Value::Number(v) if v.is_positive())
 	}
 
+	pub fn is_negative(&self) -> bool {
+		matches!(self, Value::Number(v) if v.is_negative())
+	}
+
+	pub fn is_zero_or_positive(&self) -> bool {
+		matches!(self, Value::Number(v) if v.is_zero_or_positive())
+	}
+
+	pub fn is_zero_or_negative(&self) -> bool {
+		matches!(self, Value::Number(v) if v.is_zero_or_negative())
+	}
+
 	pub fn is_datetime(&self) -> bool {
 		matches!(self, Value::Datetime(_))
 	}