Quantum: WIP: Add doc comments, parse unquoted values into numbers

2021-02-08T06:21:54Z

WIP: Add doc comments, parse unquoted values into numbers

@@ Line 1: / Line 1: @@
 local p = {}
 function p.parse_string(s)
      local result = {}
@@ Line 46: / Line 54: @@
      return result
 end
@@ Line 79: / Line 63: @@
 -- Attempt to consume an unquoted value, e.g., the "bar" in "foo: bar"
 function match_unquoted_value(s, init)
-     return match_pattern(s, "^(([^,:()]+)%s*)", init)
+     local value, i = match_pattern(s, "^(([^,:()]+)%s*)", init)
 end
@@ Line 97: / Line 86: @@
 function match_whitespace(s, init)
      return match_pattern(s, "^((%s*))", init)
 end
 return p

Quantum: WIP: Parser for a simple data-structure DSL, because templates only let you pass in strings

2021-02-08T05:47:17Z

WIP: Parser for a simple data-structure DSL, because templates only let you pass in strings

New page

local p = {}

function p.parse_string(s)
local result = {}

-- Strip leading whitespace
local i = 1
local token = ""
token, i = match_whitespace(s, i)

-- Parse each key-value pair
while i <= #s do
local key = nil
local value = nil

-- optional key, if present
token, i = match_key(s, i)
if token ~= nil then
key = token
end

-- value
token, i = match_unquoted_value(s, i)
if token == nil then
token, i = match_quoted_value(s, i)
end
if token == nil then
error("Parse error: expected a value at position " .. i .. " of: " .. s)
end
value = token

-- Save key:value pair
-- No key means append to end of table
if key == nil then
table.insert(result, value)
else
result[key] = value
end

-- Consume separator between key-value pairs
token, i = match_separator(s, i)
if token == nil and i <= #s then
error("Parse error: expected comma at position " .. i .. " of: " .. s)
end
end

return result
end

--[[
Attempts to "consume" a pattern from a string. Example:

s = "foo bar baz"
offset = 1
word, offset = match_pattern(s, "((foo)%s*)", offset)
-- word = "foo", offset = 5
word, offset = match_pattern(s, "((bar)%s*)", offset)
-- word = "bar", offset = 9
word, offset = match_pattern(s, "((whoops!)%s*)", offset)
-- word = nil, offset = 9
-- (offset doesn't change on failure)

Pattern must have two capture groups: the entire string, and the portion
of interest (the thing that is returned along with the new offset).
]]
function match_pattern(s, pattern, init)
full, content = string.match(s, pattern, init)
if full == nil then
return nil, init
end
return content, init + #full
end

-- Attempt to consume a key name, e.g., the "foo" in "foo: bar"
function match_key(s, init)
return match_pattern(s, "^(([%a_][%w_]*)%s*:%s*)", init)
end

-- Attempt to consume an unquoted value, e.g., the "bar" in "foo: bar"
function match_unquoted_value(s, init)
return match_pattern(s, "^(([^,:()]+)%s*)", init)
end

-- Attempt to consume a quoted value, e.g., the ":::" in "dots: (:::)"
function match_quoted_value(s, init)
local quoted, i = match_pattern(s, "^((%b())%s*)", init)
local unquoted = string.sub(quoted, 2, -2)
return unquoted, i
end

-- Attempt to match a comma, e.g., the "," in "foo: 1, bar: 2"
function match_separator(s, init)
return match_pattern(s, "^((,)%s*)", init)
end

-- Attempt to match leading whitespace, e.g., the " " in " foo:bar"
function match_whitespace(s, init)
return match_pattern(s, "^((%s*))", init)
end

return p

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Quantum: WIP: Add doc comments, parse unquoted values into numbers

Quantum: WIP: Parser for a simple data-structure DSL, because templates only let you pass in strings