[m-rev.] for review: parsing_utils, allow optional + sign in float exponent

[Peter Wang]

Branches: main, 11.07

library/parsing_utils.m:
	Let float_literal, float_literal_as_string accept an optional plus sign
	in the exponent.  This matches the syntax for Mercury and many other
	languages.

tests/general/test_parsing_utils.m:
tests/general/test_parsing_utils.exp:
tests/general/test_parsing_utils.exp2:
	Update test case.

diff --git a/library/parsing_utils.m b/library/parsing_utils.m
index 66e1151..d1135ed 100644
--- a/library/parsing_utils.m
+++ b/library/parsing_utils.m
@@ -202,7 +202,7 @@
     %
 :- pred eof(src::in, unit::out, ps::in, ps::out) is semidet.
 
-    % Parse a float literal matching [-][0-9]+[.][0-9]+([Ee][-][0-9]+)?
+    % Parse a float literal matching [-][0-9]+[.][0-9]+([Ee][-+][0-9]+)?
     % followed by any whitespace.  The float_literal_as_string version simply
     % returns the matched string.  The float_literal version uses
     % string.to_float to convert the output of float_literal_as_string; this
@@ -828,7 +828,7 @@ float_literal_as_string(Src, FloatStr, !PS) :-
     next_char(Src, ('.'), !PS),
     digits(10, Src, _, !PS),
     ( if char_in_class("eE", Src, _, !PS) then
-        ( if next_char(Src, ('-'), !PS) then true else true ),
+        optional_sign(Src, !PS),
         digits(10, Src, _, !PS)
       else
         true
@@ -837,6 +837,20 @@ float_literal_as_string(Src, FloatStr, !PS) :-
     skip_whitespace(Src, !PS),
     input_substring(Src, Start, EndPlusOne, FloatStr).
 
+:- pred optional_sign(src::in, ps::in, ps::out) is det.
+
+optional_sign(Src, !PS) :-
+    ( if
+        next_char(Src, Char, !PS),
+        ( Char = ('-')
+        ; Char = ('+')
+        )
+      then
+        true
+      else
+        true
+    ).
+
 %-----------------------------------------------------------------------------%
 
 float_literal(Src, Float, !PS) :-
diff --git a/tests/general/test_parsing_utils.exp b/tests/general/test_parsing_utils.exp
index fa22c89..7f9af9a 100644
--- a/tests/general/test_parsing_utils.exp
+++ b/tests/general/test_parsing_utils.exp
@@ -117,9 +117,21 @@ pass: float_literal_as_string on "-123.0   abc"
 pass: float_literal_as_string on "-123.0e1   abc"
 	returned "-123.0e1" as expected
 	[11 chars consumed]
+pass: float_literal_as_string on "-123.0e-1   abc"
+	returned "-123.0e-1" as expected
+	[12 chars consumed]
+pass: float_literal_as_string on "-123.0e+1   abc"
+	returned "-123.0e+1" as expected
+	[12 chars consumed]
+pass: float_literal_as_string on "-123.0E1   abc"
+	returned "-123.0E1" as expected
+	[11 chars consumed]
 pass: float_literal_as_string on "-123.0E-1   abc"
 	returned "-123.0E-1" as expected
 	[12 chars consumed]
+pass: float_literal_as_string on "-123.0E+1   abc"
+	returned "-123.0E+1" as expected
+	[12 chars consumed]
 pass: float_literal on ""
 	failed as expected
 pass: float_literal on "abc"
@@ -138,6 +150,9 @@ pass: float_literal on "-123.0   abc"
 pass: float_literal on "-123.0e1   abc"
 	returned -1230.0 as expected
 	[11 chars consumed]
+pass: float_literal on "-123.0e+1   abc"
+	returned -1230.0 as expected
+	[12 chars consumed]
 pass: float_literal on "-123.0E-1   abc"
 	returned -12.3 as expected
 	[12 chars consumed]
diff --git a/tests/general/test_parsing_utils.exp2 b/tests/general/test_parsing_utils.exp2
index 6f05593..64aaed1 100644
--- a/tests/general/test_parsing_utils.exp2
+++ b/tests/general/test_parsing_utils.exp2
@@ -117,9 +117,21 @@ pass: float_literal_as_string on "-123.0   abc"
 pass: float_literal_as_string on "-123.0e1   abc"
 	returned "-123.0e1" as expected
 	[11 chars consumed]
+pass: float_literal_as_string on "-123.0e-1   abc"
+	returned "-123.0e-1" as expected
+	[12 chars consumed]
+pass: float_literal_as_string on "-123.0e+1   abc"
+	returned "-123.0e+1" as expected
+	[12 chars consumed]
+pass: float_literal_as_string on "-123.0E1   abc"
+	returned "-123.0E1" as expected
+	[11 chars consumed]
 pass: float_literal_as_string on "-123.0E-1   abc"
 	returned "-123.0E-1" as expected
 	[12 chars consumed]
+pass: float_literal_as_string on "-123.0E+1   abc"
+	returned "-123.0E+1" as expected
+	[12 chars consumed]
 pass: float_literal on ""
 	failed as expected
 pass: float_literal on "abc"
@@ -138,6 +150,9 @@ pass: float_literal on "-123.0   abc"
 pass: float_literal on "-123.0e1   abc"
 	returned -1230.0 as expected
 	[11 chars consumed]
+pass: float_literal on "-123.0e+1   abc"
+	returned -1230.0 as expected
+	[12 chars consumed]
 pass: float_literal on "-123.0E-1   abc"
 	returned -12.3 as expected
 	[12 chars consumed]
diff --git a/tests/general/test_parsing_utils.m b/tests/general/test_parsing_utils.m
index e9f0460..86e5625 100644
--- a/tests/general/test_parsing_utils.m
+++ b/tests/general/test_parsing_utils.m
@@ -245,7 +245,15 @@ test_case("float_literal_as_string", stringify(float_literal_as_string),
 test_case("float_literal_as_string", stringify(float_literal_as_string),
     "-123.0e1   abc", yes("\"-123.0e1\"")).
 test_case("float_literal_as_string", stringify(float_literal_as_string),
+    "-123.0e-1   abc", yes("\"-123.0e-1\"")).
+test_case("float_literal_as_string", stringify(float_literal_as_string),
+    "-123.0e+1   abc", yes("\"-123.0e+1\"")).
+test_case("float_literal_as_string", stringify(float_literal_as_string),
+    "-123.0E1   abc", yes("\"-123.0E1\"")).
+test_case("float_literal_as_string", stringify(float_literal_as_string),
     "-123.0E-1   abc", yes("\"-123.0E-1\"")).
+test_case("float_literal_as_string", stringify(float_literal_as_string),
+    "-123.0E+1   abc", yes("\"-123.0E+1\"")).
 
 test_case("float_literal", stringify(float_literal),
     "", no).
@@ -262,6 +270,8 @@ test_case("float_literal", stringify(float_literal),
 test_case("float_literal", stringify(float_literal),
     "-123.0e1   abc", yes("-1230.0")).
 test_case("float_literal", stringify(float_literal),
+    "-123.0e+1   abc", yes("-1230.0")).
+test_case("float_literal", stringify(float_literal),
     "-123.0E-1   abc", yes("-12.3")).
 
 test_case("int_literal_as_string", stringify(int_literal_as_string),

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