lexer: Reimplement for better testability and internationalization.

[pspp-builds.git] / doc / language.texi

diff --git a/doc/language.texi b/doc/language.texi
index 6226741463a4086a1d7021e3c159f4043918c0ab..5381668c705ad38675c924d2147858a8b2790c82 100644 (file)
--- a/doc/language.texi
+++ b/doc/language.texi
@@ -3,12 +3,6 @@
 @cindex language, PSPP
 @cindex PSPP, language
 
 @cindex language, PSPP
 @cindex PSPP, language
 

-@quotation
-@strong{Please note:} PSPP is not even close to completion.
-Only a few statistical procedures are implemented.  PSPP
-is a work in progress.
-@end quotation
-

 This chapter discusses elements common to many PSPP commands.
 Later chapters will describe individual commands in detail.
 
 This chapter discusses elements common to many PSPP commands.
 Later chapters will describe individual commands in detail.
 


@@ -117,27 +111,29 @@ character used for quoting in the string, double it, e.g.@:
 significant inside strings.
 
 Strings can be concatenated using @samp{+}, so that @samp{"a" + 'b' +
 significant inside strings.
 
 Strings can be concatenated using @samp{+}, so that @samp{"a" + 'b' +

-'c'} is equivalent to @samp{'abc'}.  Concatenation is useful for
-splitting a single string across multiple source lines. The maximum
-length of a string, after concatenation, is 255 characters.
-
-Strings may also be expressed as hexadecimal, octal, or binary
-character values by prefixing the initial quote character by @samp{X},
-@samp{O}, or @samp{B} or their lowercase equivalents.  Each pair,
-triplet, or octet of characters, according to the radix, is
-transformed into a single character with the given value.  If there is
-an incomplete group of characters, the missing final digits are
-assumed to be @samp{0}.  These forms of strings are nonportable
-because numeric values are associated with different characters by
-different operating systems.  Therefore, their use should be confined
-to syntax files that will not be widely distributed.
-
-@cindex characters, reserved
-@cindex 0
-@cindex white space
-The character with value 00 is reserved for
-internal use by PSPP.  Its use in strings causes an error and
-replacement by a space character.
+'c'} is equivalent to @samp{'abc'}.  So that a long string may be
+broken across lines, a line break may precede or follow, or both
+precede and follow, the @samp{+}.  (However, an entirely blank line
+preceding or following the @samp{+} is interpreted as ending the
+current command.)
+
+Strings may also be expressed as hexadecimal character values by
+prefixing the initial quote character by @samp{x} or @samp{X}.
+Regardless of the syntax file or active dataset's encoding, the
+hexadecimal digits in the string are interpreted as Unicode characters
+in UTF-8 encoding.
+
+Individual Unicode code points may also be expressed by specifying the
+hexadecimal code point number in single or double quotes preceded by
+@samp{u} or @samp{U}.  For example, Unicode code point U+1D11E, the
+musical G clef character, could be expressed as @code{U'1D11E'}.
+Invalid Unicode code points (above U+10FFFF or in between U+D800 and
+U+DFFF) are not allowed.
+
+When strings are concatenated with @samp{+}, each segment's prefix is
+considered individually.  For example, @code{'The G clef symbol is:' +
+u"1d11e" + "."} inserts a G clef symbol in the middle of an otherwise
+plain text string.

 
 @item Punctuators and Operators
 @cindex punctuators
 
 @item Punctuators and Operators
 @cindex punctuators


@@ -154,11 +150,6 @@ punctuator only as the last character on a line (except white space).
 When it is the last non-space character on a line, a period is not
 treated as part of another token, even if it would otherwise be part
 of, e.g.@:, an identifier or a floating-point number.
 When it is the last non-space character on a line, a period is not
 treated as part of another token, even if it would otherwise be part
 of, e.g.@:, an identifier or a floating-point number.

-
-Actually, the character that ends a command can be changed with
-@cmd{SET}'s ENDCMD subcommand (@pxref{SET}), but we do not recommend
-doing so.  Throughout the remainder of this manual we will assume that
-the default setting is in effect.

 @end table
 
 @node Commands
 @end table
 
 @node Commands


@@ -186,38 +177,43 @@ by a forward slash (@samp{/}).
 There are multiple ways to mark the end of a command.  The most common
 way is to end the last line of the command with a period (@samp{.}) as
 described in the previous section (@pxref{Tokens}).  A blank line, or
 There are multiple ways to mark the end of a command.  The most common
 way is to end the last line of the command with a period (@samp{.}) as
 described in the previous section (@pxref{Tokens}).  A blank line, or

-one that consists only of white space or comments, also ends a command
-by default, although you can use the NULLINE subcommand of @cmd{SET}
-to disable this feature (@pxref{SET}).
+one that consists only of white space or comments, also ends a command.

 
 @node Syntax Variants
 
 @node Syntax Variants

-@section Variants of syntax.
+@section Syntax Variants

 
 @cindex Batch syntax
 @cindex Interactive syntax
 
 
 @cindex Batch syntax
 @cindex Interactive syntax
 

-There are two variants of command syntax, @i{viz}: @dfn{batch} mode and
-@dfn{interactive} mode.
-Batch mode is the default when reading commands from a file.
-Interactive mode is the default when commands are typed at a prompt
-by a user.
-Certain commands, such as @cmd{INSERT} (@pxref{INSERT}), may explicitly
-change the syntax mode. 
-
-In batch mode, any line that contains a non-space character
-in the leftmost column begins a new command. 
-Thus, each command consists of a flush-left line followed by any
-number of lines indented from the left margin. 
-In this mode, a plus or minus sign (@samp{+}, @samp{@minus{}}) as the
-first character in a line is ignored and causes that line to begin a
-new command, which allows for visual indentation of a command without
-that command being considered part of the previous command. 
-The period terminating the end of a command is optional but recommended.
-
-In interactive mode, each command must  either be terminated with a period,
-or an empty line must follow the command.
-The use of (@samp{+} and @samp{@minus{}} as continuation characters is not
-permitted.
+There are three variants of command syntax, which vary only in how
+they detect the end of one command and the start of the next.
+
+In @dfn{interactive mode}, which is the default for syntax typed at a
+command prompt, a period as the last non-blank character on a line
+ends a command.  A blank line also ends a command.
+
+In @dfn{batch mode}, an end-of-line period or a blank line also ends a
+command.  Additionally, it treats any line that has a non-blank
+character in the leftmost column as beginning a new command.  Thus, in
+batch mode the second and subsequent lines in a command must be
+indented.
+
+Regardless of the syntax mode, a plus sign, minus sign, or period in
+the leftmost column of a line is ignored and causes that line to begin
+a new command.  This is most useful in batch mode, in which the first
+line of a new command could not otherwise be indented, but it is
+accepted regardless of syntax mode.
+
+The default mode for reading commands from a file is @dfn{auto mode}.
+It is the same as batch mode, except that a line with a non-blank in
+the leftmost column only starts a new command if that line begins with
+the name of a PSPP command.  This correctly interprets most valid PSPP
+syntax files regardless of the syntax mode for which they are
+intended.
+
+The @option{--interactive} (or @option{-i}) or @option{--batch} (or
+@option{-b}) options set the syntax mode for files listed on the PSPP
+command line.  @xref{Main Options}, for more details.

 
 @node Types of Commands
 @section Types of Commands
 
 @node Types of Commands
 @section Types of Commands


@@ -381,9 +377,7 @@ spaces.
 Variables, whether numeric or string, can have designated
 @dfn{user-missing values}.  Every user-missing value is an actual value
 for that variable.  However, most of the time user-missing values are
 Variables, whether numeric or string, can have designated
 @dfn{user-missing values}.  Every user-missing value is an actual value
 for that variable.  However, most of the time user-missing values are

-treated in the same way as the system-missing value.  String variables
-that are wider than a certain width, usually 8 characters (depending on
-computer architecture), cannot have user-missing values.
+treated in the same way as the system-missing value.

 
 For more information on missing values, see the following sections:
 @ref{Variables}, @ref{MISSING VALUES}, @ref{Expressions}.  See also the
 
 For more information on missing values, see the following sections:
 @ref{Variables}, @ref{MISSING VALUES}, @ref{Expressions}.  See also the


@@ -449,13 +443,9 @@ Numeric or string.
 @item Width
 (string variables only) String variables with a width of 8 characters or
 fewer are called @dfn{short string variables}.  Short string variables
 @item Width
 (string variables only) String variables with a width of 8 characters or
 fewer are called @dfn{short string variables}.  Short string variables

-can be used in many procedures where @dfn{long string variables} (those
+may be used in a few contexts where @dfn{long string variables} (those

 with widths greater than 8) are not allowed.
 
 with widths greater than 8) are not allowed.
 

-Certain systems may consider strings longer than 8
-characters to be short strings.  Eight characters represents a minimum
-figure for the maximum length of a short string.
-

 @item Position
 Variables in the dictionary are arranged in a specific order.
 @cmd{DISPLAY} can be used to show this order: see @ref{DISPLAY}.
 @item Position
 Variables in the dictionary are arranged in a specific order.
 @cmd{DISPLAY} can be used to show this order: see @ref{DISPLAY}.