* lisp/emacs-lisp/smie.el: Improve warnings and conflict detection.
(smie-warning-count): New var. (smie-set-prec2tab): Use it. (smie-bnf->prec2): Improve warnings. Add docstring. (smie-bnf--closer-alist): Rename from smie-bnf-closer-alist. (smie-bnf--set-class): New function. (smie-bnf--classify): Rename from smie-bnf-classify. Rewrite to fix corner case.
This commit is contained in:
Stefan Monnier
parent
b50a28de87
commit
2ad52c605c
2 changed files with 118 additions and 46 deletions
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@ -1,5 +1,14 @@
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2011-11-18 Stefan Monnier <monnier@iro.umontreal.ca>
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* emacs-lisp/smie.el: Improve warnings and conflict detection.
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(smie-warning-count): New var.
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(smie-set-prec2tab): Use it.
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(smie-bnf->prec2): Improve warnings. Add docstring.
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(smie-bnf--closer-alist): Rename from smie-bnf-closer-alist.
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(smie-bnf--set-class): New function.
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(smie-bnf--classify): Rename from smie-bnf-classify. Rewrite to fix
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corner case.
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* progmodes/compile.el: Obey compilation-first-column in dest buffer.
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(compilation-error-properties, compilation-move-to-column):
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Handle compilation-first-column while in the target buffer.
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@ -69,13 +69,23 @@
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;; (exp ("IF" exp "ELSE" exp "END") ("CASE" cases "END"))
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;; (cases (cases "ELSE" insts) ...)
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;; The IF-rule implies ELSE=END and the CASE-rule implies ELSE>END.
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;; FIXME: we could try to resolve such conflicts automatically by changing
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;; the way BNF rules such as the IF-rule is handled. I.e. rather than
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;; IF=ELSE and ELSE=END, we could turn them into IF<ELSE and ELSE>END
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;; and IF=END,
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;; This can be resolved simply with:
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;; (exp ("IF" expelseexp "END") ("CASE" cases "END"))
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;; (expelseexp (exp) (exp "ELSE" exp))
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;; (cases (cases "ELSE" insts) ...)
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;; - Another source of conflict is when a terminator/separator is used to
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;; terminate elements at different levels, as in:
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;; (decls ("VAR" vars) (decls "," decls))
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;; (vars (id) (vars "," vars))
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;; often these can be resolved by making the lexer distinguish the two
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;; kinds of commas, e.g. based on the following token.
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;; TODO & BUGS:
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;;
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;; - We could try to resolve conflicts such as the IFexpELSEexpEND -vs-
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;; CASE(casesELSEexp)END automatically by changing the way BNF rules such as
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;; the IF-rule is handled. I.e. rather than IF=ELSE and ELSE=END, we could
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;; turn them into IF<ELSE and ELSE>END and IF=END.
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;; - Using the structural information SMIE gives us, it should be possible to
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;; implement a `smie-align' command that would automatically figure out what
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;; there is to align and how to do it (something like: align the token of
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@ -107,6 +117,10 @@
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;;; Code:
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;; FIXME:
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;; - smie-indent-comment doesn't interact well with mis-indented lines (where
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;; the indent rules don't do what the user wants). Not sure what to do.
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(eval-when-compile (require 'cl))
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(defgroup smie nil
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@ -138,6 +152,8 @@
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;; turns them into a levels table, which is what's used by the rest of
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;; the SMIE code.
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(defvar smie-warning-count 0)
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(defun smie-set-prec2tab (table x y val &optional override)
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(assert (and x y))
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(let* ((key (cons x y))
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@ -149,7 +165,8 @@
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;; be able to distinguish the two cases so that overrides
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;; don't hide real conflicts.
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(puthash key (gethash key override) table)
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(display-warning 'smie (format "Conflict: %s %s/%s %s" x old val y)))
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(display-warning 'smie (format "Conflict: %s %s/%s %s" x old val y))
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(incf smie-warning-count))
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(puthash key val table))))
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(put 'smie-precs->prec2 'pure t)
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@ -193,21 +210,54 @@ one of those elements share the same precedence level and associativity."
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prec2)))
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(put 'smie-bnf->prec2 'pure t)
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(defun smie-bnf->prec2 (bnf &rest precs)
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(defun smie-bnf->prec2 (bnf &rest resolvers)
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"Convert the BNF grammar into a prec2 table.
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BNF is a list of nonterminal definitions of the form:
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\(NONTERM RHS1 RHS2 ...)
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where each RHS is a (non-empty) list of terminals (aka tokens) or non-terminals.
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Not all grammars are accepted:
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- an RHS cannot be an empty list (this is not needed, since SMIE allows all
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non-terminals to match the empty string anyway).
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- an RHS cannot have 2 consecutive non-terminals: between each non-terminal
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needs to be a terminal (aka token). This is a fundamental limitation of
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the parsing technology used (operator precedence grammar).
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Additionally, conflicts can occur:
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- The returned prec2 table holds constraints between pairs of
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token, and for any given pair only one constraint can be
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present, either: T1 < T2, T1 = T2, or T1 > T2.
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- A token can either be an `opener' (something similar to an open-paren),
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a `closer' (like a close-paren), or `neither' of the two (e.g. an infix
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operator, or an inner token like \"else\").
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Conflicts can be resolved via RESOLVERS, which is a list of elements that can
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be either:
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- a precs table (see `smie-precs->prec2') to resolve conflicting constraints,
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- a constraint (T1 REL T2) where REL is one of = < or >."
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;; FIXME: Add repetition operator like (repeat <separator> <elems>).
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;; Maybe also add (or <elem1> <elem2>...) for things like
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;; (exp (exp (or "+" "*" "=" ..) exp)).
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;; Basically, make it EBNF (except for the specification of a separator in
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;; the repetition, maybe).
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(let ((nts (mapcar 'car bnf)) ;Non-terminals
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(first-ops-table ())
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(last-ops-table ())
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(first-nts-table ())
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(last-nts-table ())
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(prec2 (make-hash-table :test 'equal))
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(override (apply 'smie-merge-prec2s
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(mapcar 'smie-precs->prec2 precs)))
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again)
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(let* ((nts (mapcar 'car bnf)) ;Non-terminals.
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(first-ops-table ())
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(last-ops-table ())
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(first-nts-table ())
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(last-nts-table ())
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(smie-warning-count 0)
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(prec2 (make-hash-table :test 'equal))
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(override
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(let ((precs ())
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(over (make-hash-table :test 'equal)))
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(dolist (resolver resolvers)
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(cond
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((and (= 3 (length resolver)) (memq (nth 1 resolver) '(= < >)))
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(smie-set-prec2tab
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over (nth 0 resolver) (nth 2 resolver) (nth 1 resolver)))
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((memq (caar resolver) '(left right assoc nonassoc))
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(push resolver precs))
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(t (error "Unknown resolver %S" resolver))))
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(apply #'smie-merge-prec2s over
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(mapcar 'smie-precs->prec2 precs))))
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again)
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(dolist (rules bnf)
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(let ((nt (car rules))
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(last-ops ())
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@ -287,8 +337,11 @@ one of those elements share the same precedence level and associativity."
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(setq rhs (cdr rhs)))))
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;; Keep track of which tokens are openers/closer, so they can get a nil
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;; precedence in smie-prec2->grammar.
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(puthash :smie-open/close-alist (smie-bnf-classify bnf) prec2)
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(puthash :smie-closer-alist (smie-bnf-closer-alist bnf) prec2)
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(puthash :smie-open/close-alist (smie-bnf--classify bnf) prec2)
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(puthash :smie-closer-alist (smie-bnf--closer-alist bnf) prec2)
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(if (> smie-warning-count 0)
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(display-warning
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'smie (format "Total: %d warnings" smie-warning-count)))
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prec2))
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;; (defun smie-prec2-closer-alist (prec2 include-inners)
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@ -343,7 +396,7 @@ one of those elements share the same precedence level and associativity."
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;; openers)
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;; alist)))
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(defun smie-bnf-closer-alist (bnf &optional no-inners)
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(defun smie-bnf--closer-alist (bnf &optional no-inners)
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;; We can also build this closer-alist table from a prec2 table,
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;; but it takes more work, and the order is unpredictable, which
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;; is a problem for smie-close-block.
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@ -371,37 +424,33 @@ from the table, e.g. the table will not include things like (\"if\" . \"else\").
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(pushnew (cons (car rhs) term) alist :test #'equal)))))))
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(nreverse alist)))
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(defun smie-bnf-classify (bnf)
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(defun smie-bnf--set-class (table token class)
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(let ((prev (gethash token table class)))
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(puthash token
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(cond
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((eq prev class) class)
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((eq prev t) t) ;Non-terminal.
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(t (display-warning
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'smie
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(format "token %s is both %s and %s" token class prev))
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'neither))
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table)))
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(defun smie-bnf--classify (bnf)
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"Return a table classifying terminals.
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Each terminal can either be an `opener', a `closer', or neither."
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Each terminal can either be an `opener', a `closer', or `neither'."
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(let ((table (make-hash-table :test #'equal))
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(nts (mapcar #'car bnf))
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(alist '()))
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(dolist (category bnf)
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(puthash (car category) 'neither table) ;Remove non-terminals.
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(puthash (car category) t table)) ;Mark non-terminals.
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(dolist (category bnf)
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(dolist (rhs (cdr category))
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(if (null (cdr rhs))
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(puthash (pop rhs) 'neither table)
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(let ((first (pop rhs)))
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(puthash first
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(if (memq (gethash first table) '(nil opener))
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'opener
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(unless (member first nts)
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(error "SMIE: token %s is both opener and non-opener"
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first))
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'neither)
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table))
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(while (cdr rhs)
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(puthash (pop rhs) 'neither table)) ;Remove internals.
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(let ((last (pop rhs)))
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(puthash last
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(if (memq (gethash last table) '(nil closer))
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'closer
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(unless (member last nts)
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(error "SMIE: token %s is both closer and non-closer"
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last))
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'neither)
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table)))))
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(smie-bnf--set-class table (pop rhs) 'neither)
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(smie-bnf--set-class table (pop rhs) 'opener)
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(while (cdr rhs) ;Remove internals.
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(smie-bnf--set-class table (pop rhs) 'neither))
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(smie-bnf--set-class table (pop rhs) 'closer))))
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(maphash (lambda (tok v)
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(when (memq v '(closer opener))
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(push (cons tok v) alist)))
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@ -692,8 +741,22 @@ Possible return values:
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;; Keep looking as long as we haven't matched the
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;; topmost operator.
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(levels
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(if (numberp (funcall op-forw toklevels))
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(push toklevels levels)))
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(cond
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((numberp (funcall op-forw toklevels))
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(push toklevels levels))
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;; FIXME: For some languages, we can express the grammar
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;; OK, but next-sexp doesn't stop where we'd want it to.
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;; E.g. in SML, we'd want to stop right in front of
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;; "local" if we're scanning (both forward and backward)
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;; from a "val/fun/..." at the same level.
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;; Same for Pascal/Modula2's "procedure" w.r.t
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;; "type/var/const".
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;;
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;; ((and (functionp (cadr (funcall op-forw toklevels)))
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;; (funcall (cadr (funcall op-forw toklevels))
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;; levels))
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;; (setq levels nil))
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))
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;; We matched the topmost operator. If the new operator
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;; is the last in the corresponding BNF rule, we're done.
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((not (numberp (funcall op-forw toklevels)))
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@ -980,7 +1043,7 @@ function should return nil for arguments it does not expect.
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OFFSET can be:
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nil use the default indentation rule.
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`(column . COLUMN) indent to column COLUMN.
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\(column . COLUMN) indent to column COLUMN.
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NUMBER offset by NUMBER, relative to a base token
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which is the current token for :after and
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its parent for :before.
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