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pgsql: Revise plpgsql's scanner to process comments and string literals

From: tgl(at)postgresql(dot)org (Tom Lane)
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Revise plpgsql's scanner to process comments and string literals
Date: 2009-04-19 18:52:58
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Lists: pgsql-committers
Log Message:
Revise plpgsql's scanner to process comments and string literals in a way
more nearly matching the core SQL scanner.  The user-visible effects are:

* Block comments (slash-star comments) now nest, as per SQL spec.

* In standard_conforming_strings mode, backslash as the last character of a
  non-E string literal is now correctly taken as an ordinary character;
  formerly it was misinterpreted as escaping the ending quote.  (Since the
  string also had to pass through the core scanner, this invariably led
  to syntax errors.)

* Formerly, backslashes in the format string of RAISE were always treated as
  quoting the next character, regardless of mode.  Now, they are ordinary
  characters with standard_conforming_strings on, while with it off, they
  introduce the same set of escapes as in the core SQL scanner.  Also,
  escape_string_warning is now effective for RAISE format strings.  These
  changes make RAISE format strings work just like any other string literal.

This is implemented by copying and pasting a lot of logic from the core
scanner.  It would be a good idea to look into getting rid of plpgsql's
scanner entirely in favor of using the core scanner.  However, that involves
more change than I can justify making during beta --- in particular, the core
scanner would have to become re-entrant.

In passing, remove the kluge that made the plpgsql scanner emit T_FUNCTION or
T_TRIGGER as a made-up first token.  That presumably had some value once upon
a time, but now it's just useless complication for both the scanner and the

Modified Files:
        plpgsql.sgml (r1.139 -> r1.140)
        gram.y (r1.121 -> r1.122)
        pl_comp.c (r1.134 -> r1.135)
        pl_funcs.c (r1.76 -> r1.77)
        plpgsql.h (r1.110 -> r1.111)
        scan.l (r1.67 -> r1.68)
        plpgsql.out (r1.70 -> r1.71)
        plpgsql.sql (r1.59 -> r1.60)

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