Added a topological sort algorithm, for use when dumping.

- tsort.h, tsort.c, Makefile: stable topological sort with priorities
- fpd.l, fpd.y: added directive %tsort to test-drive the sort algorithm
- README: documented %tsort



git-svn-id: http://svn.openmoko.org/trunk/eda/fped@5942 99fdad57-331a-0410-800a-d7fa5415bdb3

Makefile

@@ -16,7 +16,7 @@ UPLOAD = werner@sita.openmoko.org:public_html/fped/
 
 OBJS = fped.o expr.o coord.o obj.o delete.o inst.o util.o error.o \
        unparse.o file.o dump.o kicad.o postscript.o meas.o \
-       layer.o overlap.o hole.o \
+       layer.o overlap.o hole.o tsort.o \
        cpp.o lex.yy.o y.tab.o \
        gui.o gui_util.o gui_style.o gui_inst.o gui_status.o gui_canvas.o \
        gui_tool.o gui_over.o gui_meas.o gui_frame.o gui_frame_drag.o

README

@@ -582,14 +582,15 @@ would print "width = 1mm"
 Experimental: debugging directives
 ----------------------------------
 
-For debugging and regression tests, fped supports the following commands
+For debugging and regression tests, fped supports the following commands,
-that mimick the effect of GUI operations:
+most of which mimick the effect of GUI operations:
 
 %del <identifier>
 %move <identifier> [<number>] <identifier>
 %print <expression>
 %dump
 %exit
+%tsort { -<id> | +<id> | <id-before> <id-after> [<number>] ... }
 
 %del and %move take as their first argument the name of the vector or
 object to manipulate. For this purpose, also objects can be labeled.
@@ -608,3 +609,8 @@ anchor index	vec/frame	line/rect/pad	arc		measurement
 
 %dump writes the footprint definition in the fped language to standard
 output. %exit immediately exits fped, without invoking the GUI.
+
+%tsort is used to test-drive the topological sort algorithm. The items
+in the curly braces are declarations of nodes with (-<id>) or without
+(+<id>) decay or edges in the partial order. The optional number is
+the edge's priority. See tsort.c for details.

TODO

@@ -69,7 +69,6 @@ Future directions:
 - live update of value when entering strings and expressions ?
 - advanced: non-standard solder mask
 - advanced: solder paste exceptions (subtractive, additive)
-- advanced: holes
 - advanced: silk line width
 - future: consider editing non-canvas items (e.g., variable names/values) in
   place

fpd.l

@@ -133,6 +133,8 @@ SP	[\t ]*
 				  return TOK_DBG_DUMP; }
 <INITIAL>"%exit"		{ BEGIN(NOKEYWORD);
 				  return TOK_DBG_EXIT; }
+<INITIAL>"%tsort"		{ BEGIN(NOKEYWORD);
+				  return TOK_DBG_TSORT; }
 
 <INITIAL>[a-zA-Z_][a-zA-Z_0-9]*: { *strchr(yytext, ':') = 0;
 				  yylval.id = unique(yytext);

fpd.y

@@ -22,6 +22,7 @@
 #include "meas.h"
 #include "gui_status.h"
 #include "dump.h"
+#include "tsort.h"
 #include "fpd.h"
 
 
@@ -46,6 +47,8 @@ static int n_vars, n_values;
 
 static const char *id_sin, *id_cos, *id_sqrt;
 
+static struct tsort *tsort;
+
 
 static struct frame *find_frame(const char *name)
 {
@@ -289,7 +292,7 @@ static void append_root_frame(void)
 %token		TOK_MEAS TOK_MEASX TOK_MEASY TOK_UNIT
 %token		TOK_NEXT TOK_NEXT_INVERTED TOK_MAX TOK_MAX_INVERTED
 %token		TOK_DBG_DEL TOK_DBG_MOVE TOK_DBG_PRINT TOK_DBG_DUMP
-%token		TOK_DBG_EXIT
+%token		TOK_DBG_EXIT TOK_DBG_TSORT
 
 %token	<num>	NUMBER
 %token	<str>	STRING
@@ -481,6 +484,39 @@ debug_item:
 		{
 			exit(0);
 		}
+	| TOK_DBG_TSORT '{'
+		{
+			tsort = begin_tsort();
+		}
+	    sort_items '}'
+		{
+			void **sort, **walk;
+
+			sort = end_tsort(tsort);
+			for (walk = sort; *walk; walk++)
+				printf("%s\n", (char *) *walk);
+			free(sort);
+		}
+	;
+
+sort_items:
+	| sort_items '+' ID
+		{
+			add_node(tsort, (void *) $3, 0);
+		}
+	| sort_items '-' ID
+		{
+			add_node(tsort, (void *) $3, 1);
+		}
+	| sort_items ID ID opt_num
+		{
+			struct node *a, *b;
+
+			/* order is important here ! */
+			a = add_node(tsort, (void *) $2, 0);
+			b = add_node(tsort, (void *) $3, 0);
+			add_edge(a, b, $4.n);
+		}
 	;
 
 table:

tsort.c

@@ -0,0 +1,160 @@
+/*
+ * tsort.c - Topological sort
+ *
+ * Written 2010 by Werner Almesberger
+ * Copyright 2010 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * We use a slight variation of Kahn's algorithm. The difference is that we add
+ * a priority. Edges with the highest priority get selected before edges with
+ * lower priority.
+ *
+ * We maintain the initial list of nodes in the order in which they were added.
+ * Therefore, the first node with inbound edges will always be sorted first.
+ * E.g., the root frame.
+ *
+ * add_node and add_edge can be invoked multiple times with the same
+ * parameters. In the case of add_node, simply the existing node is returned.
+ * In the case of add_edge, the new edge's priority is added to the priority of
+ * the previous edges.
+ *
+ * Priority is accumulated in a node until the node is output. If a node has
+ * the "decay" flag set, it resets the priorities of all other nodes when
+ * output. E.g., when outputting a vector, all priorities accumulated from
+ * previous vectors (towards referencing them with ".") lose their effect.
+ *
+ * Last but not least, the algorithm is stable: a pre-existing order that
+ * conflicts neither with the partial order nor the priorities is preserved.
+ *
+ * Thus, we have the following sorting criteria, in decreasing importance:
+ * - the destination if an edge never precedes its origin
+ * - higher priority comes before lower priority
+ * - earlier add_node comes before later
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+
+#include "util.h"
+#include "tsort.h"
+
+
+struct edge {
+	struct node *to;
+	int priority;		/* edge priority */
+	struct edge *next;
+};
+
+struct node {
+	void *user;
+	struct edge *edges;	/* outbound edges */
+	int incoming;		/* number of incoming edges */
+	int priority;		/* cumulative node priority */
+	int decay;		/* all node prio. decay after issuing this */
+	struct node *next;
+};
+
+struct tsort {
+	struct node *nodes;
+	struct node **next_node;
+	int n_nodes;
+};
+
+
+void add_edge(struct node *from, struct node *to, int priority)
+{
+	struct edge **edge;
+
+	for (edge = &from->edges; *edge; edge = &(*edge)->next)
+		if ((*edge)->to == to) {
+			(*edge)->priority += priority;
+			return;
+		}
+	*edge = alloc_type(struct edge);
+	(*edge)->to = to;
+	(*edge)->priority = priority;
+	(*edge)->next = NULL;
+	to->incoming++;
+}
+
+
+struct node *add_node(struct tsort *tsort, void *user, int decay)
+{
+	struct node *node;
+
+	for (node = tsort->nodes; node; node = node->next)
+		if (node->user == user)
+			return node;
+	node = alloc_type(struct node);
+	node->user = user;
+	node->edges = NULL;
+	node->incoming = 0;
+	node->priority = 0;
+	node->decay = decay;
+	node->next = NULL;
+	*tsort->next_node = node;
+	tsort->next_node = &node->next;
+	tsort->n_nodes++;
+	return node;
+}
+
+
+struct tsort *begin_tsort(void)
+{
+	struct tsort *tsort;
+
+	tsort = alloc_type(struct tsort);
+	tsort->nodes = NULL;
+	tsort->next_node = &tsort->nodes;
+	tsort->n_nodes = 0;
+	return tsort;
+}
+
+
+void **end_tsort(struct tsort *tsort)
+{
+	struct node **walk, **first, *node;
+	struct edge *edge;
+	void **res;
+	int n = 0;
+
+	res = alloc_size(sizeof(void *)*(tsort->n_nodes+1));
+	while (1) {
+		first = NULL;
+		for (walk = &tsort->nodes; *walk; walk = &(*walk)->next) {
+			if ((*walk)->incoming)
+				continue;
+			if (!first || (*first)->priority < (*walk)->priority)
+				first = walk;
+		}
+		if (!first)
+			break;
+		if ((*first)->decay)
+			for (node = tsort->nodes; node; node = node->next)
+				node->priority = 0;
+		node = *first;
+		*first = node->next;
+		res[n++] = node->user;
+		while (node->edges) {
+			edge = node->edges;
+			edge->to->incoming--;
+			edge->to->priority += edge->priority;
+			node->edges = edge->next;
+			free(edge);
+		}
+		free(node);
+	}
+	if (tsort->nodes) /* we have at least one cycle */
+		abort();
+	free(tsort);
+	res[n] = NULL;
+	return res;
+}

tsort.h

@@ -0,0 +1,25 @@
+/*
+ * tsort.h - Topological sort
+ *
+ * Written 2010 by Werner Almesberger
+ * Copyright 2010 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef TSORT_H
+#define TSORT_H
+
+struct node;
+struct tsort;
+
+struct node *add_node(struct tsort *tsort, void *user, int decay);
+void add_edge(struct node *from, struct node *to, int priority);
+
+struct tsort *begin_tsort(void);
+void **end_tsort(struct tsort *tsort);
+
+#endif /* !TSORT_H */