-@node Language, Expressions, Invocation, Top
+@node Language
@chapter The 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.
@menu
* Tokens:: Characters combine to form tokens.
* Commands:: Tokens combine to form commands.
+* Syntax Variants:: Batch vs. Interactive mode
* Types of Commands:: Commands come in several flavors.
* Order of Commands:: Commands combine to form syntax files.
* Missing Observations:: Handling missing observations.
* BNF:: How command syntax is described.
@end menu
-@node Tokens, Commands, Language, Language
+
+@node Tokens
@section Tokens
@cindex language, lexical analysis
@cindex language, tokens
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
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, Types of Commands, Tokens, Language
+@node Commands
@section Forming commands of tokens
@cindex PSPP, command structure
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}).
-
-In batch mode only, that is, when reading commands from a file instead
-of an interactive user, 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.
-
-@node Types of Commands, Order of Commands, Commands, Language
+one that consists only of white space or comments, also ends a command.
+
+@node Syntax Variants
+@section Syntax Variants
+
+@cindex Batch syntax
+@cindex Interactive syntax
+
+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
Commands in PSPP are divided roughly into six categories:
active file (the data) to be read.
@end table
-@node Order of Commands, Missing Observations, Types of Commands, Language
+@node Order of Commands
@section Order of Commands
@cindex commands, ordering
@cindex order of commands
@end itemize
@end table
-@node Missing Observations, Variables, Order of Commands, Language
+@node Missing Observations
@section Handling missing observations
@cindex missing values
@cindex values, missing
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
documentation on individual procedures for information on how they
handle missing values.
-@node Variables, Files, Missing Observations, Language
+@node Variables
@section Variables
@cindex variables
@cindex dictionary
* Scratch Variables:: Variables deleted by procedures.
@end menu
-@node Attributes, System Variables, Variables, Variables
+@node Attributes
@subsection Attributes of Variables
@cindex variables, attributes of
@cindex attributes of 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.
-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 Write format
Similar to print format, but used by the @cmd{WRITE} command
(@pxref{WRITE}).
+
+@cindex custom attributes
+@item Custom attributes
+User-defined associations between names and values. @xref{VARIABLE
+ATTRIBUTE}.
@end table
-@node System Variables, Sets of Variables, Attributes, Variables
+@node System Variables
@subsection Variables Automatically Defined by PSPP
@cindex system variables
@cindex variables, system
Page width, in characters, in format F3.
@end table
-@node Sets of Variables, Input and Output Formats, System Variables, Variables
+@node Sets of Variables
@subsection Lists of variable names
-@cindex TO convention
-@cindex convention, TO
+@cindex @code{TO} convention
+@cindex convention, @code{TO}
To refer to a set of variables, list their names one after another.
Optionally, their names may be separated by commas. To include a
another command with this method, the same set can be referenced on
later commands using the same syntax.
-@node Input and Output Formats, Scratch Variables, Sets of Variables, Variables
+@node Input and Output Formats
@subsection Input and Output Formats
+@cindex formats
An @dfn{input format} describes how to interpret the contents of an
input field as a number or a string. It might specify that the field
contains an ordinary decimal number, a time or date, a number in binary
@node Basic Numeric Formats
@subsubsection Basic Numeric Formats
+@cindex numeric formats
The basic numeric formats are used for input and output of real numbers
in standard or scientific notation. The following table shows an
example of how each format displays positive and negative numbers with
@float
@multitable {DOLLAR10.2} {@code{@tie{}$3,141.59}} {@code{-$3,141.59}}
-@headitem Format @tab @code{@tie{}}3141.59 @tab -3141.59
+@headitem Format @tab @code{@tie{}3141.59} @tab @code{-3141.59}
@item F8.2 @tab @code{@tie{}3141.59} @tab @code{-3141.59}
@item COMMA9.2 @tab @code{@tie{}3,141.59} @tab @code{-3,141.59}
@item DOT9.2 @tab @code{@tie{}3.141,59} @tab @code{-3.141,59}
@node Custom Currency Formats
@subsubsection Custom Currency Formats
+@cindex currency formats
The custom currency formats are closely related to the basic numeric
formats, but they allow users to customize the output format. The
SET command configures custom currency formats, using the syntax
@float
@multitable {CCD13.2} {@code{@tie{}@tie{}USD 3,145.59}} {@code{(USD 3,145.59)}}
-@headitem Format @tab @code{@tie{}}3145.59 @tab -3145.59
+@headitem Format @tab @code{@tie{}3145.59} @tab @code{-3145.59}
@item CCA12.2 @tab @code{@tie{}EUR3,145.59} @tab @code{EUR3,145.59-}
@item CCB14.2 @tab @code{@tie{}@tie{}USD 3,145.59} @tab @code{(USD 3,145.59)}
@item CCC11.2 @tab @code{@tie{}R$3.145,59} @tab @code{-R$3.145,59}
@node Binary and Hexadecimal Numeric Formats
@subsubsection Binary and Hexadecimal Numeric Formats
+@cindex binary formats
+@cindex hexadecimal formats
The binary and hexadecimal formats are primarily designed for
compatibility with existing machine formats, not for human readability.
All of them therefore have a F format as default output format. Some of
@node Time and Date Formats
@subsubsection Time and Date Formats
+@cindex time formats
+@cindex date formats
In PSPP, a @dfn{time} is an interval. The time formats translate
between human-friendly descriptions of time intervals and PSPP's
internal representation of time intervals, which is simply the number of
The maximum width for time and date formats is 40 columns. Minimum
input and output width for each of the time and date formats is shown
below:
+
@float
@multitable {DATETIME} {Min. Input Width} {Min. Output Width} {4-digit year}
@headitem Format @tab Min. Input Width @tab Min. Output Width @tab Option
@node String Formats
@subsubsection String Formats
+@cindex string formats
The A and AHEX formats are the only ones that may be assigned to string
variables. Neither format allows any decimal places.
input, uppercase and lowercase are both accepted. The default output
format is A format with half the input width.
-@node Scratch Variables, , Input and Output Formats, Variables
+@node Scratch Variables
@subsection Scratch Variables
+@cindex scratch variables
Most of the time, variables don't retain their values between cases.
Instead, either they're being read from a data file or the active file,
in which case they assume the value read, or, if created with
name of a file as a string, that is, enclosed within @samp{'} or
@samp{"}.
+A file name string that begins or ends with @samp{|} is treated as the
+name of a command to pipe data to or from. You can use this feature
+to read data over the network using a program such as @samp{curl}
+(e.g.@: @code{GET '|curl -s -S http://example.com/mydata.sav'}), to
+read compressed data from a file using a program such as @samp{zcat}
+(e.g.@: @code{GET '|zcat mydata.sav.gz'}), and for many other
+purposes.
+
PSPP also supports declaring named file handles with the @cmd{FILE
HANDLE} command. This command associates an identifier of your choice
(the file handle's name) with a file. Later, the file handle name can
@dfn{start symbol}. The start symbol defines the entire syntax for
that command.
@end itemize
-@setfilename ignored
projects / pspp-builds.git / blobdiff