From b0f8ed6b56dcc534db986fae8840b9381eb37f78 Mon Sep 17 00:00:00 2001
From: Tobie Morgan Hitchcock <tobie@abcum.com>
Date: Wed, 9 Nov 2016 15:15:09 +0000
Subject: [PATCH] Improving parsing of time durations.
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Previously, the number 0 was parsed as 0ns.

In addition, it is now not possible to have duration values defined as strings (inside “” or ‘’).

However, now values are explicitly marked as a duration only if they have a valid DURATION suffix. Anlything else is either a NUMBER of an IDENT.
---
 sql/scanner.go | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/sql/scanner.go b/sql/scanner.go
index cb819126..2504f79d 100644
--- a/sql/scanner.go
+++ b/sql/scanner.go
@@ -578,8 +578,24 @@ func (s *scanner) scanNumber(chp ...rune) (tok Token, lit string, val interface{
 		} else if isNumber(ch) {
 			buf.WriteRune(ch)
 		} else if isLetter(ch) {
-			tok = IDENT
-			buf.WriteRune(ch)
+			if tok == NUMBER || tok == DOUBLE {
+				tok = IDENT
+				buf.WriteRune(ch)
+				switch ch {
+				case 's', 'h', 'd', 'w':
+					tok = DURATION
+				case 'n', 'u', 'µ', 'm':
+					if chn := s.next(); chn == 's' {
+						tok = DURATION
+						buf.WriteRune(chn)
+					} else {
+						s.undo()
+					}
+				}
+			} else {
+				tok = IDENT
+				buf.WriteRune(ch)
+			}
 		} else if ch == '.' {
 			if tok == DOUBLE {
 				tok = IDENT
@@ -594,10 +610,6 @@ func (s *scanner) scanNumber(chp ...rune) (tok Token, lit string, val interface{
 		}
 	}
 
-	if val, err := time.ParseDuration(buf.String()); err == nil {
-		return DURATION, buf.String(), val
-	}
-
 	return tok, buf.String(), nil
 
 }
@@ -663,10 +675,6 @@ func (s *scanner) scanString(chp ...rune) (tok Token, lit string, val interface{
 		}
 	}
 
-	if val, err := time.ParseDuration(buf.String()); err == nil {
-		return DURATION, buf.String(), val
-	}
-
 	if val, err := time.Parse(RFCDate, buf.String()); err == nil {
 		return DATE, buf.String(), val.UTC()
 	}
@@ -826,7 +834,7 @@ func isNumber(ch rune) bool {
 
 // isLetter returns true if the rune is a letter.
 func isLetter(ch rune) bool {
-	return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')
+	return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || ch == 'µ'
 }
 
 // isIdentChar returns true if the rune is allowed in a IDENT.