Project P111
Config merger
Settings in three layers - defaults, environment, command line - merged deeply with the source of every value, against a shallow merge that loses sibling settings and a merge that tests values for truth and lets false, 0 and empty text fall through.
2 modules · 2 recorded sessionstext-menu UI in the terminalupdated 2026-10-16
Every screen below was recorded under CPython. When this page was built, the EML interpreter replayed each session from the same input and printed the same bytes.
About
Settings in three layers, defaults, environment and command line, each later layer over the earlier ones. The deep merge is set against a shallow merge and against a merge that tests values for truth.
main.eml- the menu, the layers and the merge with each value's source, the two comparisons, setting a key, and where a key comes fromlayers.eml- paths, the deep, shallow and truth-testing merges, the merge of all layers with sources, and reading paths and values
How each part works:
- Each layer is a set of leaves written as dotted paths, such as server.tls.cert. A value is true, false, a whole number, or text.
- The deep merge, as in the corpus case
nested-config-merge: a later layer replaces exactly the leaves it sets. A leaf it sets removes the same path, every path under it, and any value above it that was not a table. It is the same as merging nested tables recursively, which the check confirms. - The shallow merge replaces each top-level key a later layer names, whole. Setting server.tls.enabled in the environment loses server.host, server.port and server.tls.cert.
- The truth-testing merge, as in the corpus case
config-defaults-merge, makes the mistake of asking whether a value is true instead of whether it is set. A later false, 0 or '' then falls through to the layer below. - Each merged value names the last layer that set it.
What is checked: menu choices 1 to 6; one of the three layers; a setting as path=value or path=unset; a path of lower-case words, digits, _ and - joined by dots; a value of true, false, a whole number of up to nine digits without a leading zero, 'text', or a word of letters, digits and - _ . / :. An empty answer cancels.
Sessions: sessions/basic.in gives: - the three layers and the merge, with each value's source; - the shallow merge, which loses four leaves; - the truth-testing merge, which loses log.verbose=false, retries=0 and name=''; - where server.tls.cert and retries come from; - server set to 'off' on the command line, which replaces the whole server table; server.port explained; then server removed again; - log.level set in the environment, and the shallow merge again.
sessions/bad-input.in gives: - menu choices 0 and x; - settings: a cancel, an unknown layer, a cancel, no =, no path, upper case, two dots, a quote inside a word, a space in a value, and removing a key that is not there; - paths: a cancel, a bad one, and one no layer sets; - server.port=007, kept as text because of its leading zeros.
Built on the verified corpus cases nested-config-merge (if both values are tables, recurse instead of replacing) and config-defaults-merge (presence is not truthiness).
Recorded sessions
What the screen shows while someone uses the program. Each typed line appears after its prompt, the way a terminal shows it.
bad-input
interpreter: byte-equal== Config merger ==
Settings in three layers - defaults, environment, command line - each later one over the earlier ones.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 0
Pick a number from 1 to 6.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> x
Pick a number from 1 to 6.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)>
Cancelled.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> prod
Type defaults, environment or command line.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting>
Cancelled.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> server.port
Type path=value.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> =3
Type path=value.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> Server.Port=1
A path is lower-case words, digits, _ and - joined by dots.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> a..b=1
A path is lower-case words, digits, _ and - joined by dots.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> x=it's
A value is true, false, a whole number, 'text', or a word of letters, digits and - _ . / :.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> x=a b
A value is true, false, a whole number, 'text', or a word of letters, digits and - _ . / :.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> nothing=unset
nothing is not set in defaults.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 5
path>
Cancelled.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 5
path> Bad Path
A path is lower-case words, digits, _ and - joined by dots.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 5
path> colour
defaults -
environment -
command line -
No layer sets it.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> defaults
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> server.port=007
server.port = '007' in defaults.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 1
defaults:
log.level 'info'
log.verbose true
name 'app'
retries 3
server.host 'app.example'
server.port '007'
server.tls.cert 'certs/app.pem'
server.tls.enabled false
environment:
log.verbose false
server.tls.enabled true
command line:
name ''
retries 0
Merged, each later layer over the earlier ones:
log.level 'info' from defaults
log.verbose false from environment
name '' from command line
retries 0 from command line
server.host 'app.example' from defaults
server.port '007' from defaults
server.tls.cert 'certs/app.pem' from defaults
server.tls.enabled true from environment
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 6
Bye.
What was typed (41 lines)
0
x
4
4
prod
4
defaults
4
defaults
server.port
4
defaults
=3
4
defaults
Server.Port=1
4
defaults
a..b=1
4
defaults
x=it's
4
defaults
x=a b
4
defaults
nothing=unset
5
5
Bad Path
5
colour
4
defaults
server.port=007
1
6
basic
interpreter: byte-equal== Config merger ==
Settings in three layers - defaults, environment, command line - each later one over the earlier ones.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 1
defaults:
log.level 'info'
log.verbose true
name 'app'
retries 3
server.host 'app.example'
server.port 8080
server.tls.cert 'certs/app.pem'
server.tls.enabled false
environment:
log.verbose false
server.tls.enabled true
command line:
name ''
retries 0
Merged, each later layer over the earlier ones:
log.level 'info' from defaults
log.verbose false from environment
name '' from command line
retries 0 from command line
server.host 'app.example' from defaults
server.port 8080 from defaults
server.tls.cert 'certs/app.pem' from defaults
server.tls.enabled true from environment
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 2
Where the shallow merge differs from the deep one:
log.level 'info' lost by the shallow merge
server.host 'app.example' lost by the shallow merge
server.port 8080 lost by the shallow merge
server.tls.cert 'certs/app.pem' lost by the shallow merge
A shallow merge replaces every top-level key a later layer names, so setting one leaf under a top-level key loses every other leaf under that key.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 3
Where the truth-testing merge differs from the deep one:
log.verbose false the truth-testing merge has true, from defaults
name '' the truth-testing merge has 'app', from defaults
retries 0 the truth-testing merge has 3, from defaults
Testing a value for truth instead of asking whether it was set lets false, 0 and '' fall through to the layer below.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 5
path> server.tls.cert
defaults 'certs/app.pem'
environment -
command line -
Merged: 'certs/app.pem', from defaults: the last layer that sets it.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 5
path> retries
defaults 3
environment -
command line 0
Merged: 0, from command line: the last layer that sets it.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> command line
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> server=off
server = 'off' in command line.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 1
defaults:
log.level 'info'
log.verbose true
name 'app'
retries 3
server.host 'app.example'
server.port 8080
server.tls.cert 'certs/app.pem'
server.tls.enabled false
environment:
log.verbose false
server.tls.enabled true
command line:
name ''
retries 0
server 'off'
Merged, each later layer over the earlier ones:
log.level 'info' from defaults
log.verbose false from environment
name '' from command line
retries 0 from command line
server 'off' from command line
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 5
path> server.port
defaults 8080
environment -
command line -
Merged: not set - a later layer replaced it.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> command line
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> server=unset
server removed from command line.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 4
layer (defaults, environment or command line)> environment
As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.
setting> log.level=debug
log.level = 'debug' in environment.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 2
Where the shallow merge differs from the deep one:
server.host 'app.example' lost by the shallow merge
server.port 8080 lost by the shallow merge
server.tls.cert 'certs/app.pem' lost by the shallow merge
A shallow merge replaces every top-level key a later layer names, so setting one leaf under a top-level key loses every other leaf under that key.
1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit
choice> 6
Bye.
What was typed (21 lines)
1
2
3
5
server.tls.cert
5
retries
4
command line
server=off
1
5
server.port
4
command line
server=unset
4
environment
log.level=debug
2
6
Modules
The program as written, entry module first. Each module transpiles to its own Python file, which is what eml project run executes.
main.eml(entry)
eml# P111 config merger: settings in three layers merged deeply, against a
# shallow merge and against a merge that tests values for truth.
import layers
def plain(s):
0 => i
len(s) => j
while i < j and s[i] == " ":
i + 1 => i
while j > i and s[j - 1] == " ":
j - 1 => j
return s[i:j]
def pad(s, n):
while len(s) < n:
s + " " => s
return s
def show_layers(ls):
for l in ls:
(" " + l[0] + ":") ^0
layers.sorted_paths(l[1]) => ps
if len(ps) == 0:
" (nothing)" ^0
for p in ps:
(" " + pad(p, 22) + layers.show(l[1][p])) ^0
layers.merged(ls, "deep") => m
"Merged, each later layer over the earlier ones:" ^0
for p in layers.sorted_paths(m[0]):
(" " + pad(p, 22) + pad(layers.show(m[0][p]), 20) + "from " + m[1][p]) ^0
def compare(ls, mode, what):
layers.merged(ls, "deep") => good
layers.merged(ls, mode) => other
[] => lines
for p in layers.sorted_paths(good[0]):
if not (p in other[0]):
lines + [" " + pad(p, 22) + pad(layers.show(good[0][p]), 20) + "lost by the " + what + " merge"] => lines
elif not layers.same(good[0][p], other[0][p]):
lines + [" " + pad(p, 22) + pad(layers.show(good[0][p]), 20) + "the " + what + " merge has " + layers.show(other[0][p]) + ", from " + other[1][p]] => lines
for p in layers.sorted_paths(other[0]):
if not (p in good[0]):
lines + [" " + pad(p, 22) + pad("(not set)", 20) + "the " + what + " merge has " + layers.show(other[0][p])] => lines
if len(lines) == 0:
("The " + what + " merge gives the same settings here.") ^0
return
("Where the " + what + " merge differs from the deep one:") ^0
for line in lines:
line ^0
if mode == "shallow":
"A shallow merge replaces every top-level key a later layer names, so setting one leaf under a top-level key loses every other leaf under that key." ^0
else:
"Testing a value for truth instead of asking whether it was set lets false, 0 and '' fall through to the layer below." ^0
def ask_layer(ls):
plain(input("layer (defaults, environment or command line)> ")) => n
if n == "":
return -1
for k in [0:len(ls) - 1]:
if ls[k][0] == n:
return k
"Type defaults, environment or command line." ^0
return -2
def set_key(ls):
ask_layer(ls) => k
if k == -1:
"Cancelled." ^0
return ls
if k == -2:
return ls
"As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it." ^0
plain(input("setting> ")) => t
if t == "":
"Cancelled." ^0
return ls
-1 => eq
for i in [0:len(t) - 1]:
if eq == -1 and t[i] == "=":
i => eq
if eq < 1:
"Type path=value." ^0
return ls
t[0:eq] => p
t[eq + 1:len(t)] => v
if not layers.path_ok(p):
"A path is lower-case words, digits, _ and - joined by dots." ^0
return ls
ls[k][1] => d
if v == "unset":
if not (p in d):
(p + " is not set in " + ls[k][0] + ".") ^0
return ls
{} => nd
for q in d:
if q != p:
d[q] => nd[q]
nd => ls[k][1]
(p + " removed from " + ls[k][0] + ".") ^0
return ls
layers.parse_value(v) => val
if len(val) == 0:
"A value is true, false, a whole number, 'text', or a word of letters, digits and - _ . / :." ^0
return ls
{} => nd
[] => gone
for q in d:
if layers.shadows(p, q) and q != p:
gone + [q] => gone
elif q != p:
d[q] => nd[q]
val => nd[p]
nd => ls[k][1]
(p + " = " + layers.show(val) + " in " + ls[k][0] + ".") ^0
if len(gone) > 0:
"" => line
for q in gone:
if line != "":
line + ", " => line
line + q => line
(" It replaces " + line + " in the same layer.") ^0
return ls
def explain(ls):
plain(input("path> ")) => p
if p == "":
"Cancelled." ^0
return
if not layers.path_ok(p):
"A path is lower-case words, digits, _ and - joined by dots." ^0
return
False => any
for l in ls:
if p in l[1]:
True => any
(" " + pad(l[0], 14) + layers.show(l[1][p])) ^0
else:
(" " + pad(l[0], 14) + "-") ^0
layers.merged(ls, "deep") => m
if p in m[0]:
("Merged: " + layers.show(m[0][p]) + ", from " + m[1][p] + ": the last layer that sets it.") ^0
elif any:
("Merged: not set - a later layer replaced it.") ^0
else:
"No layer sets it." ^0
[["defaults", {"server.host": ["str", "app.example"], "server.port": ["int", "8080"], "server.tls.enabled": ["bool", "false"], "server.tls.cert": ["str", "certs/app.pem"], "log.level": ["str", "info"], "log.verbose": ["bool", "true"], "retries": ["int", "3"], "name": ["str", "app"]}], ["environment", {"server.tls.enabled": ["bool", "true"], "log.verbose": ["bool", "false"]}], ["command line", {"retries": ["int", "0"], "name": ["str", ""]}]] => ls
"== Config merger ==" ^0
"Settings in three layers - defaults, environment, command line - each later one over the earlier ones." ^0
True => running
while running:
"" ^0
"1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit" ^0
plain(input("choice> ")) => choice
if choice == "1":
show_layers(ls)
elif choice == "2":
compare(ls, "shallow", "shallow")
elif choice == "3":
compare(ls, "truthy", "truth-testing")
elif choice == "4":
set_key(ls) => ls
elif choice == "5":
explain(ls)
elif choice == "6":
False => running
else:
"Pick a number from 1 to 6." ^0
"Bye." ^0
Python projection (main.py)
import layers
def plain(s):
i = 0
j = len(s)
while i < j and s[i] == " ":
i = i + 1
while j > i and s[j - 1] == " ":
j = j - 1
return s[i:j]
def pad(s, n):
while len(s) < n:
s = s + " "
return s
def show_layers(ls):
for l in ls:
print(" " + l[0] + ":")
ps = layers.sorted_paths(l[1])
if len(ps) == 0:
print(" (nothing)")
for p in ps:
print(" " + pad(p, 22) + layers.show(l[1][p]))
m = layers.merged(ls, "deep")
print("Merged, each later layer over the earlier ones:")
for p in layers.sorted_paths(m[0]):
print(" " + pad(p, 22) + pad(layers.show(m[0][p]), 20) + "from " + m[1][p])
def compare(ls, mode, what):
good = layers.merged(ls, "deep")
other = layers.merged(ls, mode)
lines = []
for p in layers.sorted_paths(good[0]):
if not p in other[0]:
lines = lines + [" " + pad(p, 22) + pad(layers.show(good[0][p]), 20) + "lost by the " + what + " merge"]
elif not layers.same(good[0][p], other[0][p]):
lines = lines + [" " + pad(p, 22) + pad(layers.show(good[0][p]), 20) + "the " + what + " merge has " + layers.show(other[0][p]) + ", from " + other[1][p]]
for p in layers.sorted_paths(other[0]):
if not p in good[0]:
lines = lines + [" " + pad(p, 22) + pad("(not set)", 20) + "the " + what + " merge has " + layers.show(other[0][p])]
if len(lines) == 0:
print("The " + what + " merge gives the same settings here.")
return
print("Where the " + what + " merge differs from the deep one:")
for line in lines:
print(line)
if mode == "shallow":
print("A shallow merge replaces every top-level key a later layer names, so setting one leaf under a top-level key loses every other leaf under that key.")
else:
print("Testing a value for truth instead of asking whether it was set lets false, 0 and '' fall through to the layer below.")
def ask_layer(ls):
n = plain(input("layer (defaults, environment or command line)> "))
if n == "":
return -1
for k in range(0, len(ls)):
if ls[k][0] == n:
return k
print("Type defaults, environment or command line.")
return -2
def set_key(ls):
k = ask_layer(ls)
if k == -1:
print("Cancelled.")
return ls
if k == -2:
return ls
print("As path=value, such as server.port=9000, log.verbose=false, name='' - or path=unset to remove it.")
t = plain(input("setting> "))
if t == "":
print("Cancelled.")
return ls
eq = -1
for i in range(0, len(t)):
if eq == -1 and t[i] == "=":
eq = i
if eq < 1:
print("Type path=value.")
return ls
p = t[0:eq]
v = t[eq + 1:len(t)]
if not layers.path_ok(p):
print("A path is lower-case words, digits, _ and - joined by dots.")
return ls
d = ls[k][1]
if v == "unset":
if not p in d:
print(p + " is not set in " + ls[k][0] + ".")
return ls
nd = {}
for q in d:
if q != p:
nd[q] = d[q]
ls[k][1] = nd
print(p + " removed from " + ls[k][0] + ".")
return ls
val = layers.parse_value(v)
if len(val) == 0:
print("A value is true, false, a whole number, 'text', or a word of letters, digits and - _ . / :.")
return ls
nd = {}
gone = []
for q in d:
if layers.shadows(p, q) and q != p:
gone = gone + [q]
elif q != p:
nd[q] = d[q]
nd[p] = val
ls[k][1] = nd
print(p + " = " + layers.show(val) + " in " + ls[k][0] + ".")
if len(gone) > 0:
line = ""
for q in gone:
if line != "":
line = line + ", "
line = line + q
print(" It replaces " + line + " in the same layer.")
return ls
def explain(ls):
p = plain(input("path> "))
if p == "":
print("Cancelled.")
return
if not layers.path_ok(p):
print("A path is lower-case words, digits, _ and - joined by dots.")
return
any = False
for l in ls:
if p in l[1]:
any = True
print(" " + pad(l[0], 14) + layers.show(l[1][p]))
else:
print(" " + pad(l[0], 14) + "-")
m = layers.merged(ls, "deep")
if p in m[0]:
print("Merged: " + layers.show(m[0][p]) + ", from " + m[1][p] + ": the last layer that sets it.")
elif any:
print("Merged: not set - a later layer replaced it.")
else:
print("No layer sets it.")
ls = [["defaults", {"server.host": ["str", "app.example"], "server.port": ["int", "8080"], "server.tls.enabled": ["bool", "false"], "server.tls.cert": ["str", "certs/app.pem"], "log.level": ["str", "info"], "log.verbose": ["bool", "true"], "retries": ["int", "3"], "name": ["str", "app"]}], ["environment", {"server.tls.enabled": ["bool", "true"], "log.verbose": ["bool", "false"]}], ["command line", {"retries": ["int", "0"], "name": ["str", ""]}]]
print("== Config merger ==")
print("Settings in three layers - defaults, environment, command line - each later one over the earlier ones.")
running = True
while running:
print("")
print("1) layers and merge 2) deep against shallow 3) set against true 4) set a key 5) where a key comes from 6) quit")
choice = plain(input("choice> "))
if choice == "1":
show_layers(ls)
elif choice == "2":
compare(ls, "shallow", "shallow")
elif choice == "3":
compare(ls, "truthy", "truth-testing")
elif choice == "4":
ls = set_key(ls)
elif choice == "5":
explain(ls)
elif choice == "6":
running = False
else:
print("Pick a number from 1 to 6.")
print("Bye.")
layers.eml
eml# P111 config merger - settings in three layers (defaults, environment,
# command line), each a set of leaves written as dotted paths such as
# server.tls.cert. A value is [kind, text]: kind "bool", "int" or "str".
#
# A deep merge, as in the corpus case nested-config-merge, lets a later
# layer replace exactly the leaves it sets: a leaf it sets removes the
# same path, every path under it, and any value above it that was not a
# table. A shallow merge replaces each top-level key wholesale, so setting
# server.tls.enabled loses server.tls.cert. And as in the corpus case
# config-defaults-merge, a value is set when its key is present, not when
# it is true: false, 0 and '' must still win.
def starts(s, p):
return len(s) >= len(p) and s[0:len(p)] == p
def first(path):
for i in [0:len(path) - 1]:
if path[i] == ".":
return path[0:i]
return path
def sorted_paths(d):
[] => out
for k in d:
out + [k] => out
for i in [1:len(out) - 1]:
i => j
while j > 0 and out[j] < out[j - 1]:
out[j] => t
out[j - 1] => out[j]
t => out[j - 1]
j - 1 => j
return out
def copy(d):
{} => out
for k in d:
d[k] => out[k]
return out
def shadows(p, q):
# setting leaf p removes leaf q
return q == p or starts(q, p + ".") or starts(p, q + ".")
def deep(base, over):
{} => out
for q in base:
True => keep
for p in over:
if shadows(p, q):
False => keep
if keep:
base[q] => out[q]
for p in over:
over[p] => out[p]
return out
def shallow(base, over):
# every top-level key the later layer names is replaced whole
{} => tops
for p in over:
True => tops[first(p)]
{} => out
for q in base:
if not (first(q) in tops):
base[q] => out[q]
for p in over:
over[p] => out[p]
return out
def truthy(v):
if v[0] == "bool":
return v[1] == "true"
if v[0] == "int":
return v[1] != "0"
return v[1] != ""
def truthy_deep(base, over):
# the mistake: a later value counts only when it is true
{} => kept
for p in over:
if truthy(over[p]):
over[p] => kept[p]
return deep(base, kept)
def merged(layers, mode):
# mode "deep", "shallow" or "truthy"; [result, source of each leaf]
{} => out
{} => source
for k in [0:len(layers) - 1]:
layers[k][1] => over
if mode == "shallow":
shallow(out, over) => out
elif mode == "truthy":
truthy_deep(out, over) => out
else:
deep(out, over) => out
for p in out:
if p in over and (mode != "truthy" or truthy(over[p])):
layers[k][0] => source[p]
return [out, source]
def show(v):
if v[0] == "str":
return "'" + v[1] + "'"
return v[1]
def same(a, b):
return a[0] == b[0] and a[1] == b[1]
def path_ok(p):
if len(p) == 0 or len(p) > 40 or p[0] == "." or p[len(p) - 1] == ".":
return False
"" => prev
for c in p:
if c == "." and prev == ".":
return False
if not ((c >= "a" and c <= "z") or (c >= "0" and c <= "9") or c == "_" or c == "-" or c == "."):
return False
c => prev
return True
def parse_value(t):
# [kind, text] or []: true, false, a whole number, 'text', or a bare word
if t == "true" or t == "false":
return ["bool", t]
if len(t) >= 2 and t[0] == "'" and t[len(t) - 1] == "'":
t[1:len(t) - 1] => inner
for c in inner:
if c == "'":
return []
return ["str", inner]
t => digits
if len(t) > 0 and t[0] == "-":
t[1:len(t)] => digits
if len(digits) > 0 and len(digits) <= 9:
True => num
for c in digits:
if not (c >= "0" and c <= "9"):
False => num
if num and (len(digits) == 1 or digits[0] != "0") and not (t[0] == "-" and digits == "0"):
return ["int", t]
if len(t) == 0 or len(t) > 40:
return []
for c in t:
if not ((c >= "a" and c <= "z") or (c >= "A" and c <= "Z") or (c >= "0" and c <= "9") or c == "-" or c == "_" or c == "." or c == "/" or c == ":"):
return []
return ["str", t]
Python projection (layers.py)
def starts(s, p):
return len(s) >= len(p) and s[0:len(p)] == p
def first(path):
for i in range(0, len(path)):
if path[i] == ".":
return path[0:i]
return path
def sorted_paths(d):
out = []
for k in d:
out = out + [k]
for i in range(1, len(out)):
j = i
while j > 0 and out[j] < out[j - 1]:
t = out[j]
out[j] = out[j - 1]
out[j - 1] = t
j = j - 1
return out
def copy(d):
out = {}
for k in d:
out[k] = d[k]
return out
def shadows(p, q):
return q == p or starts(q, p + ".") or starts(p, q + ".")
def deep(base, over):
out = {}
for q in base:
keep = True
for p in over:
if shadows(p, q):
keep = False
if keep:
out[q] = base[q]
for p in over:
out[p] = over[p]
return out
def shallow(base, over):
tops = {}
for p in over:
tops[first(p)] = True
out = {}
for q in base:
if not first(q) in tops:
out[q] = base[q]
for p in over:
out[p] = over[p]
return out
def truthy(v):
if v[0] == "bool":
return v[1] == "true"
if v[0] == "int":
return v[1] != "0"
return v[1] != ""
def truthy_deep(base, over):
kept = {}
for p in over:
if truthy(over[p]):
kept[p] = over[p]
return deep(base, kept)
def merged(layers, mode):
out = {}
source = {}
for k in range(0, len(layers)):
over = layers[k][1]
if mode == "shallow":
out = shallow(out, over)
elif mode == "truthy":
out = truthy_deep(out, over)
else:
out = deep(out, over)
for p in out:
if p in over and (mode != "truthy" or truthy(over[p])):
source[p] = layers[k][0]
return [out, source]
def show(v):
if v[0] == "str":
return "'" + v[1] + "'"
return v[1]
def same(a, b):
return a[0] == b[0] and a[1] == b[1]
def path_ok(p):
if len(p) == 0 or len(p) > 40 or p[0] == "." or p[len(p) - 1] == ".":
return False
prev = ""
for c in p:
if c == "." and prev == ".":
return False
if not (c >= "a" and c <= "z" or c >= "0" and c <= "9" or c == "_" or c == "-" or c == "."):
return False
prev = c
return True
def parse_value(t):
if t == "true" or t == "false":
return ["bool", t]
if len(t) >= 2 and t[0] == "'" and t[len(t) - 1] == "'":
inner = t[1:len(t) - 1]
for c in inner:
if c == "'":
return []
return ["str", inner]
digits = t
if len(t) > 0 and t[0] == "-":
digits = t[1:len(t)]
if len(digits) > 0 and len(digits) <= 9:
num = True
for c in digits:
if not (c >= "0" and c <= "9"):
num = False
if num and (len(digits) == 1 or digits[0] != "0") and not (t[0] == "-" and digits == "0"):
return ["int", t]
if len(t) == 0 or len(t) > 40:
return []
for c in t:
if not (c >= "a" and c <= "z" or c >= "A" and c <= "Z" or c >= "0" and c <= "9" or c == "-" or c == "_" or c == "." or c == "/" or c == ":"):
return []
return ["str", t]