Re: [Patch] Expression spec: Add clarification for String compare

["Gao, Liming" <liming.gao@intel.com>]

Reviewed-by: Liming Gao <liming.gao@intel.com>

> -----Original Message-----
> From: Zhu, Yonghong
> Sent: Tuesday, October 16, 2018 9:12 AM
> To: edk2-devel@lists.01.org
> Cc: Gao, Liming <liming.gao@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Shaw, Kevin W <kevin.w.shaw@intel.com>
> Subject: [Patch] Expression spec: Add clarification for String compare
> 
> Relational and equality operators require both operands to be of
> the same type.
> Treat the string 'A' and "A" as same type, but for "A" and L"A"
> are not same type since one is general string, another is unicode
> string.
> 
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Michael Kinney <michael.d.kinney@intel.com>
> Cc: Kevin W Shaw <kevin.w.shaw@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
> ---
>  2_expression_overview.md | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/2_expression_overview.md b/2_expression_overview.md
> index c29a632..bf66ffe 100644
> --- a/2_expression_overview.md
> +++ b/2_expression_overview.md
> @@ -1,9 +1,9 @@
>  <!--- @file
>    2 Expression Overview
> 
> -  Copyright (c) 2014-2017, Intel Corporation. All rights reserved.<BR>
> +  Copyright (c) 2014-2018, Intel Corporation. All rights reserved.<BR>
> 
>    Redistribution and use in source (original document form) and 'compiled'
>    forms (converted to PDF, epub, HTML and other formats) with or without
>    modification, are permitted provided that the following conditions are met:
> 
> @@ -81,14 +81,17 @@ directives section do not apply.
> 
>  10. Multiplicative and additive operators require both operands to be
>      arithmetic in type.
> 
>  11. Relational and equality operators require both operands to be of the same
> -    type. Relational comparison on string literals and byte arrays must be
> -    performed comparing the byte values, left to right. The first pair of bytes
> -    (or a single extra byte) that is not equal will determine the result of the
> -    comparison. The following are examples of string comparisons:
> +    type. The single quote string and double quote string are same type as
> +    general string, while the string start with `L` character is the unicode
> +    string. Unicode string should not compare with general string. Relational
> +    comparison on string literals and byte arrays must be performed comparing
> +    the byte values, left to right. The first pair of bytes (or a single extra
> +    byte) that is not equal will determine the result of the comparison. The
> +    following are examples of string comparisons:
>      ```
>      Foo = "zero", Bar = "three";
>      ```
>      `Foo < Bar` will evaluate to zero (AKA, FALSE), as "z" is greater than "t".
>      ```
> --
> 2.6.1.windows.1